Special About This Number?
facts on numbers (and their peculiar properties), both mathematical
and cultural, tantalising problems and anecdotes. The number
facts in this website are also available as features for
print and electronic publishing.
free 197-page eBook containing a huge collection of number
facts is available for
you to download.
you got a distinctive fact about any number listed here you think Archimedes'
Lab community might enjoy, why not post it here?
un numero con delle proprietà originali? Contattateci!
un nombre avec des propriétés étonnantes? Contactez-nous!
dei numeri (it), liste des nombres (fr), lista de números (es,
por), Liste besonderer Zahlen (ger), getallen en getalverzamelingen (du), seznam čísel (cz), 數表 (ch), 数の一覧 (jap), список чисел (ru), שמות מספרים (he).
0-6 | 7-12 | 13-23 | 24-69 | 70-200 | 201-786 | 5H0P
number because it is the area of a 35/12, 24/5, 337/60 triangle
(a congruent number is an integer that is the area of a right
triangle with three rational number sides).
minimum number of distinct integer-sided rectangles needed to
tile a rectangle such that no 2 rectangles share a common side-length
is also the minimum number of distinct rectangles with sides in
the ratio 1:2 to perfectly tile a rectangle:
maximum number of different types of Frieze
patterns. The Frieze patterns consist of a variety of linear
transformations like reflection (mirror/lake reflection), rotation,
glide reflection and translation:
Mersenne prime (23 - 1).
is the unity digit of the number 331.
is the positive solution to: 3x2 = 16x + 35
is the divisor of 999,999
the smallest prime whose 4th power is of
the form a4 + b4 - c4:
74 = 1574 + 2274 - 2394
- posted by Morten Risager
the only integer when increased by 1 gives the double of a square,
and whose square increased by 1 gives also the double of a square:
71 + 1 = 2 x
72 + 1 = 2 x
property is used in the magic
= 5√2 ≈ 7
1 (n! + 1 is
prime for n = 1, 2, 3, 11, 27, 37, 41, 73, 77, 116, 154, 320,
340, 399, 427, and no other values below 546)
= 4 + 3 = 42 - 32
= 12 + 12 + 12 + 22 (sum
of 4 squares)
= 25 - 52
13 + 17 + 19 (sum of consecutive primes)
72 = 34 - 25
73 = 29 - 132
73 = 180 + 181 + 182 (sum
of consecutive powers of 18)
only solution to the following equations (see further above):
x = 2a2 - 1
and x2 = 2b2 - 1
(x = 7, a = 2, and b = 5)
factorial 7! = 5040 contains
50% zeroes. It seems that it is the unique factorial with this
(every ratio of the equalities above uses the digits
1 to 9 once)
= 98,532/14,076 (is
the unique pandigital ratio
that includes 0)
the number 1,014,492,753,623,188,405,797 by seven,
you just have to move the last digit 7 to the
beginning of the number: 7,101,449,275,362,318,840,579.
Numbers with such properties are called parasitic
square ends in a 7 (perfect squares can only
end in a 0, 1, 4, 5, 6, or 9).
x7 + y7 = z7 has
no solutions in integers. -- Lamé
only single digit prime number to produce a square when its cube
and the cube's proper divisors are added:
71 + 72 + 73 + 1 = 202
multiples of 7 are palindromic, such as:
77, 161, 252, 343,434, 525, 595, 616, 686, 707, 777, 868, 959,
1001, 1771, 2002, 2772, 3003, 3773, 4004, 4774, 5005, ...
smallest positive integer whose reciprocal (1/7) has a pattern
of more than one repeating digit:
1/7 = 0.142857142857142857...
It is also the smallest number for which the periodic sequence
of 1/n is of length n-1. The next such numbers
are 17, 19, 23, 29, 47, 59, 61, 97, ...
by multiplying the cyclic
number 142857 by
2, 3, 4, 5, or 6, the answer will be a cyclic permutation of itself...
2 = 285714
3 = 428571
4 = 571428
5 = 714285
6 = 857142
posted by Larry Bickford
if we square the last three digits of 142857 and
subtract the square of the first three digits, we also get
back a cyclic permutation of the number!
8572 - 1422 = 714285
/ 7 = 142857
3 to the reciprocal of 7 gives a rough approximation of Pi (3.142857...).
- (123'456'789 + 9)) / 123'456'789 = 7
Gianni A. Sarcone in 'Il Mio Computer', nr. 101 -
4938271602 - 617283952 + 617283942 -
32) / (617283952 - 617283942)
by Seven: take the digits of the number in reverse order,
from right to left, multiplying them successively by the digits 1, 3, 2, 6, 4, 5,
... (repeating with this sequence of 6 multipliers as long
as necessary). Add the products.
For example: is 1708 divisible
by 7? Well, reverse the number, 8071,
multiply and add its digits as explained, 8x1+0x3+7x2+1x6 =
28. The sum is divisible by 7, so 1708 is.
by Seven (2): for numbers having 3 digits...
154 > (2)+1+5+4+(2)
= 14 is divisible by 7, so 154 is.
245 > (4)+2+4+5+(6)
= 21 is divisible by 7, so 245 is.
862 > (2)+8+6+2+(1)
= 19 and 862 are not multiple of 7.
366 > (6)+3+6+6+(3)
= 24 and 366 are not multiple of 7.
The numbers in brackets are added in order to form with their neighbors
a 2-digit number multiple of 7. If the sum of all digits is a multiple
of 7, then the related number is divisible by 7.
- posted by Silvio Moura Velho -
a prime number
7 is a prime number
73 is a prime number
739 is a prime number
7393 is a prime number
73939 is a prime number
739391 is a prime number
7393913 is a prime number
73939133 is a prime number
(73939133 is the largest right-truncatable
the smallest number of colors needed to color the regions on
a map on a torus (donut shape).
opposite sides of a die cube always add up to 7.
piece of paper cannot be folded in half more than 7 times...
However, Britney Gallivan (of Pomona, California) found a formula that
tells us to successfully fold paper 12 times, we would need about
1.2 km of paper... and she proved it! -
posted by Chris GIbbons
Bolans of West Africa used for reckoning a kind of heptal (base-7)
positional notation system.
'letters' contains seven times itself (selfreferential
word). - G. Sarcone
Germany, a spiteful or quarrelsome woman is called eine
böse Sieben, 'an evil Seven'.
Sieben ('evil Seven') is also a stream located
in the Sachsen-Anhalt Area of the Country of Germany.
the word shi means 'death'. In some cases nana ('7'
in early classical Japanese) replaces the word shichi ('7',
in modern Japanese) because it contains shi.
symbol of the Judaic
Faith is the menorah, a 7-branch
candlestick (see opposite). According to Kabbalah (Judaic
Mysticism), God created the world with 7 divine
attributes. They are: Kindness (Chesed), Severity (Gevurah),
Harmony (Tiferet), Perseverance (Netzach),
Splendor (Hod), Attachment (Yesod) and Royalty
(Malchut). Accordingly, the entire creation is a reflection
of these seven attributes.
in the Mystical Numbers of Taoism, represents the number 7 and
symbolizes the Seven Stars -- The Big Dipper.
sjösjuka sjömän på det sjunkande skeppet
Shanghai" (seven seasick seamen on the sinking ship
Shanghai), is a Swedish tongue twister.
the 7 five-letter English words that use only
letters from the Roman numeral alphabet. [Solution]
word LUCK requires 7 penstrokes.
7 ± 2
is a cognitive numeric limit (cf. 'The Magical
Number Seven, Plus or Minus Two: Some Limits on Our Capacity
for Processing Information' by the cognitive psychologist George
A. Miller, The Psychological Review, 1956, vol. 63,
the formula of the Coca-Cola soft-drink is related to number 7.
In fact, Merchandise
7X is the "secret ingredient" in Coca-Cola
and has apparently remained a secret since its invention in 1886.
is a unit used to measure the strength of the smell from a standard
person defined as an average adult working in an office (or similar
non–industrial workplace), with a hygienic standard equivalent
of 0.7 baths per day!
Hitler was reputed to take his coffee or tea
with seven teaspoons of sugar.
7 is the Holy number. There are 7 days in creation, 7 days in the
week, 7 phases of the moon, every 7th year was sabbatical, and
7 times 7 years was the jubilee. There are 7 ages in the life of
man, 7 divisions in the Lord's Prayer, 7 bibles, 7 churches of
Asia, 7 Graces, 7 Deadly Sins, 7 Senses, 7 Sorrows of the Virgin,
7 Virtues, 7 joys of the Virgin, 7 Precious Things of the Buddhas,
7 Sleepers of Ephesus, 7 Lamps of Architecture. The apostles chose
7 deacons, Enoch, who was translated, was 7th from Adam; Jesus
Christ was the 77th in a direct line. The vision of Daniel was
70 weeks; and the elders of Israel were 70. There were also 7 heavens,
7 planets, 7 stars, 7 wise men, 7 champions of Christendom, 7 notes
in music, 7 primary colors, 7 sacraments of the Catholic Church,
and 7 wonders of the world (see below). 7 gateways were traversed
by Inanna, the most important goddess of the Sumerian pantheon,
during her descent into the underworld. The 7th son was considered
endowed with pre-eminent wisdom; and the 7th son of a 7th son is
still thought to possess the power of healing diseases spontaneously.
7 wonders of the ancient world are:
Pyramid of Giza,
Gardens of Babylon,
of Artemis at Ephesus,
of Zeus at Olympia,
of Maussollos at Halicarnassus,
- Colossus of
'Seven Blunders of the World' according to Mahatma
- Wealth without work,
- Pleasure without conscience,
- Knowledge without character,
- Commerce without morality,
- Science without humanity,
- Worship without sacrifice,
- Politics without principle
different languages (© G.
(Old English seofon)
| *SEPTM |
Sanskrit | SAPTA |
Greek, Attic | 'EΠTA HEPTA |
Latin | SEPTEM |
French sept; Spanish siete;
Catalan and Provençal set;
Portuguese setes; Romanian şapte (sometimes
pronounced as 'şepte', when
communicating telephone numbers in order to avoid a possible
confusion between 6 and 7); Rumansh siat;
Germanic | SIBUM |
German sieben; Danish syv;
Norwegian sju; Swedish sju;
Slavic | SEDMI |
|Russian семь syem';
Czech sedm; Slovenian sedem;
script' to modern sinograph 七 :
Old Chinese (pron.) | ts'yet |
|Chinese 七 qī.
The sinograph 柒 is used as a replacement for qī on
legal and financial documents.
root | Sh-B-c |
Ancient Egyptian [sfḫ-] sefekh;
|Arabic سبعة sab'a;
Hebrew שבעה sheh-vah;
Maltese: sebgha; Amharic sebat.
The roots of the word seven are hidden
in the following words: hebdomadal, heptagon, heptahedron,
september, septennial, septentrion, septuple; Bathsheba, Elizabeth.
In French: semaine, septuor.
Number (7) here.
the second honest number, because
8 = "two cubed".
is the largest cube (23) in the Fibonacci
is the smallest sum of two factorials of distinct primes: 2! +
is also the lowest number which is both a sum of prime squares
and a prime cube: 8 = 22 + 22 = 23
is the only cube that is 1 less than a square (32 -
is the 3rd number that stays the same when written upside
24 - 23
= 3122 - 463
= (7 + 7/7)! / 7!
= (3 - 1)(3 + 1)
= (1 x 2 x 3 x 4 x 5) / (1 + 2 + 3 + 4 + 5)
= 5 + 1 + 2 and 512 =
8 + 8 + 8 + 88 + 888 = 1000
you divide any square integer by 8 you get a remainder of 0,
1 or 4.
1)2 ≡ 1 (mod 8)
(... any squared odd number is a multiple of 8 plus
sums of prime pair products:
5 x 7 = 35 and 3+5 = 8
11 x 13 = 143 and 1+4+3 = 8
17 x 19 = 323 and 3+2+3 = 8
29 x 31 = 899 and 8+9+9 = 26 and 2+6 = 8
41 x 43 = 1763 and 1+7+6+3 = 17 and 1+7 = 8
59 x 61 = 3599 and 3+5+9+9 = 26 and 2+6 = 8 ... etc.
/ 123456789 = 8.0000000729000006633900060368490...
which is very nearly 8, except for the isolated
729, 66339, 6036849... Are those 3 numbers a coincidence?
base-8 (octal) numeral system was devised by the Yuki of Northern
California, who used the spaces between the fingers to count.
a term coined by earlier mathematicians to indicate the 8 power
of a number. The root word is the German zenzic from
the medieval Italian word censo. The Italians used censo to
translate the Arabic word mál (literally "possessions,
property") meaning 'squared' in the context of mathematics.
can split a pie into 8 pieces with three straight
You can also chop a big lump of cheese into a maximum of 93 bits
with just 8 straight cuts!
are 8 furlongs in a mile and 8 pints
in a gallon.
human being out of 8 is a Chinese farmer.
Inhabitants of the world (2004): 6.2 billions.
Inhabitants of China (2004): 1.3 billions, 60% of them living in
a rural area.
The proportion is then: (1.3 · 60%)/6.2
= approx. 1 Chinese farmer / 8 human beings.
--- Is this article still topical? Please send us your comments!
8-Ball is a toy made by Tyco Toys used for fortune-telling.
It was invented by Abe Bookman of the Alabe Crafts Company
in Cincinnati in 1946. Mattel holds the rights after purchasing
Tyco in 1997. A 20-sided icosahedron floats inside a murky
blue liquid inside the ball, and when you turn the ball upside
down, one of the 20 'oracles' appears.
numerology, 8 is the number of building, and
in some theories, also the number of destruction.
the main directions shown on any compass: north, northeast, east,
southeast, south, southwest, west, and northwest.
in the Mystical Numbers of Taoism, represents the number 8 and
symbolizes the Eight
Signs of Change and Combinations.
is considered a lucky number in Chinese culture because it sounds
like the word "prosper". In Northern China, people
often say: "If you want to be rich you must stick to the number
eight". Dates and times with either a 6 or an 8
have been predominantly chosen as auspicious for important events. So,
it's no coincidence that the Beijing
Olympic Games started at 08:08:08 pm!
When Chinese businessmen stay in a hotel, they would rather choose
rooms with numbers such as: 6, 8, 58, 168, 518, 588, 868, and
Immortals of the Chinese Mythology are:
Li TieGuai 李鐵拐 , Zhongli Quan 鐘離權,
Lan CaiHe 藍采和 , Zhang GuoLao 張果老 ,
He XianGu 何仙姑 , Lu DongBin 呂洞賓 ,
Han XiangZi 韓湘子 , Cao GuoJiu 曹國舅 .
Path to Enlightenment (Ārya 'ṣṭāṅga
mārgaḥ) is declared to be the way that leads to the
cessation of suffering:
View, Right Intention, Right Speech, Right Action, Right Livelihood,
Right Effort, Right Concentration, Right Mindfulness.
an eight day Jewish holiday that starts on the 25th day of December.
What did 0 say to 8? Answer: "Nice belt!".
word 'buffalo' repeated 8 times: "Buffalo
buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo" forms
a grammatically correct English sentence meaning bison from
Buffalo, New York, who are intimidated by other bison in their
community also happen to intimidate other bison in their community.
are smarter than dogs. You cannot get eight cats
to pull a sled through snow" --
different languages (© G.
(Old English eahta)
| *OKTÔ(U) |
[oktô(u) is grammatically a dual
and meant originally '2 groups of 4 fingers']
Sanskrit | ASHTA |
Greek, Attic | OKTΩ OKTÔ|
Latin | OCTO |
French huit; Spanish ocho;
Portuguese oito; Catalan vuit;
Provençal oit; Romanian opt;
Rumansh otg; Sardinian òto.
Germanic | AHTÔ |
and German acht; Danish otte;
Norwegian åtte; Swedish åtta;
Slavic | OS(T)MI |
|Russian восемь vósyem';
Czech osm; Slovenian ósem;
script' to modern sinograph 八 :
Old Chinese (pron.) | pwat |
|Chinese 八 bā.
The sinograph 捌 is used as a replacement for bā on
legal and financial documents.
root | Th-M-Ny |
Ancient Egyptian [ḫmn-] khemennu;
|Arabic ثمانيه thamâniya;
Hebrew שמונה shemônah;
Maltese: tmienja; Amharic semmint (pron.
The roots of the word eight are hidden
in the following words: OCTANS, OCTANT, OCTAVE, OCTAVO, OCTET,
OCTOBER, OCTONARY; OCTODECIMO, OCTOGENARIAN; OCTAD, OCTAGON,
OCTAHEDRON, OCTANDRY, OCTOPUS; SHEMINI ATZERETH, HESHVAN (from
Akkadian (w)aran-samnu, name of the eighth month of
the Babylonian calendar). In French: OCTANE. In Italian: OTTOCENTESCO,
Number (8) here.
the largest number of cubes needed
to sum to positive integers (in 1939, the mathematician L.E.
Dickson proved that the only integers requiring exactly 9 positive
cubes are 23 and 239).
and every 2-digit number that ends with a 9 is the sum of the
multiple of the two digits plus the sum of the two
digits. Thus, for instance: 39= (3 x 9) + (3 + 9)
= 5 + 4 = 52 - 42
= 04 + 13 +
22 + 31 + 40
= (12 +
42 + 82) = 3(13 +
63 + 83)
= 13 + 23
= 1! + 2! + 3! (sum of consecutive factorials)
= !4 = 4! (1-1/1!+1/2!-1/3!+1/4!)
= 4 + 4 + 4/4 = (4/.4)(4
- 4)! - G. Sarcone (four
= MC/C = (MD - DC)/C = CV/V - DC/L -
25 x 92 = 2592
2 3 4 5 6 7 8 9
9 8 7 6 5 4 3 2 1 0 is a mnemonic trick to remember your 9x table.
123,456,789) - 123,456,789 = 987,654,321 - 9
(in each fraction above all digits from 0 to 9 were used once)
multiplications below, digits 1-9 were used once giving pandigital products:
9 x 57,624,831 = 1,037,246,958
9 x 58,132,764 = 1,046,389,752
9 x 71,465,328 = 1,286,375,904
9 x 72,645,831 = 1,307,624,958
9 x 76,125,483 = 1,370,258,694
9 x 81,274,365 = 1,462,938,570
arrangements with 9's:
1 x 9 + 2 = 11
12 x 9 + 3 = 111
123 x 9 + 4 = 1 111
1234 x 9 + 5 = 11 111
12345 x 9 + 6 = 111 111
123456 x 9 + 7 = 1 111 111
1234567 x 9 + 8 = 11 111 111
12345678 x 9 + 9 = 111 111 111
The results above are all triangular numbers in base-9.
= 1/10 + 1/102 + 1/103 + 1/104 +
1/105 + ... = ∑i=1 10-i
the recurrent number 0.999999... denotes a real number which
is equal to 1:
9 x 1/9 = 9 x 0.111111...
Thus, 1 = 0.999999...
1.9662705 x 1077
a number containing 369,000,000 of digits!
To multiply 10,112,359,550,561,797,752,808,988,764,044,943,820,224,719
by 9 you just have to move the 9 at the very
end up to the front. Apparently, it is the only number that
(the decimal expansion is a sequence of numbers of the 9 times
table: 9, 18, 27, 36, ...)
sum 90 + 91 + 92 + … +
9n is always a triangular number.
8n – 7n +
6n – 5n + 4n – 3n +
2n – 1n with n =
2k, is a multiple of 9.
1)3 + n3 + (n + 1)3] ≡ 0
(... any sum of cubes of 3 consecutive integers
is a multiple of 9)
9 = nine + zero = eight + one = seven + two = six + three
= five + four
(the sums above contain all precisely 9
expands by about 9% as it freezes.
meters per second squared is g, the gravity constant
probability, the 'nine' is a logarithmic measure
of reliability or probability of an event, defined as the negative
of the base-10 logarithm of the probability of the event's complement.
For instance, an event that is 99% likely to occur has an unlikelihood
of 1% or 0.01, which amounts to -log10 0.01 = 2 nines of
This string of hexadecimal numbers appears to be the HD-DVD processing
key useful to decrypt and play most HD-DVD movies in Linux.
("9th day", the Roman market day): from earliest times,
a market day occurred every eight days - every 9th day, according
to the Roman method of inclusive reckoning. It was a day of rest
from agricultural labor and a time to take produce to market.
the number of fingers or toes, 10 became the base of the decimal
number system. It is the number of completeness or finality.
With ten as complete, 9 comes into prominence
as almost complete. Troy was besieged for 9 days
and fell on the tenth. Odysseus (Lat. Ulysses) wandered
for 9 years and arrived home on the tenth.
16th-century Catholic theologian Peter Bungus pointed out that
the 9th Psalm predicts the coming of the Antichrist.
In Islamic cosmology the universe is made from 9 spheres - the
traditional 8 of Ptolemy, plus a ninth added by the Arab astronomer Thābit
ibn Qurra to explain the precession of the equinoxes.
Guangdong province, China, nine is associated with eternity or
known as "Jiuxuan"), in the Mystical Numbers of Taoism,
represents the number 9 and symbolizes the Nine Chambers. It
is the last number of order before returning back to chaos. After
that, the cycle repeats...
Simpson has 9 spikes of hair
(at least, since season 2).
symbol of the Bahai
Faith is a 9-pointed star (see opposite).
full moon is nine times brighter than a half moon.
standard dimensions of a play card are: 6.35 x 9 cm.
first nine letters of the Maldivian
alphabet (h, sh, n, r, b, lh, k, ', and v) are graphically
derived from the Arabic
numerals from 1 to 9: ١, ٢, ٣, ٤, ٥, ٦, ٧, ٨, ٩.
longest one-syllable word in the English language is 9-letter long: "screeched".
different languages (© G.
(Old English nigon)
| *NEWN |
Sanskrit | NAVA |
Greek, Attic | ENNEA hennea |
Latin | NOVEM |, Archaic
Latin | NEVEN |
and Portuguese nove; French neuf;
Spanish nueve; Catalan nou;
Provençal nòu; Romanian nouă;
Rumansh nov; Sardinian nòbe.
Germanic | NIWUN |
German neun; Danish and Norwegian ni;
Swedish nio; Icelandic níu.
Slavic | DEVETI (< neveti) |
|Russian девять devyat';
Czech devět; Slovenian devét;
script' to modern sinograph 九 :
Old Chinese (pron.) | kyeu |
|Chinese 九 jiǔ.
The sinograph 玖 is used as a replacement for 九 to
prevent forgery on legal and financial documents.
root | T-Sh-' |
Ancient Egyptian [psḏ-] pest.;
|Arabic تِسْعة tisha;
Hebrew תשע tésha;
Maltese: disgħa; Amharic zethain (pron.
The roots of the word nine are hidden
in the following words: NOVEMBER, NOVENA; NONAGENARIAN; NONES,
NOON; NONAGON, NONANOIC ACID; ENNEAD, ENNEAGON.
the base of our numerical system.
is a triangular number: 1 + 2 + 3 + 4 = 10
is the only triangular number which is also the sum of 2 consecutive
square odd numbers: 12 + 32 = 10
cannot be the difference of 2 squares, because 10 is of the form
4n + 2
+ (5 - -15)
= (5 + -15)(5
= 133 – 37
= 42 – 32 + 22 – 12
= 2 + 3 + 5 (sum of the first 3 primes)
= 1 / (1 - (3 / (3 + 1/3)))
≈ π32/ e23
≈ π2 + π/24
≈ (eπ - π)/2
= 6! x 7! = 3! x 5! x 7! (Unique solution to the
factorial equation n! = a! x b! x c!
with consecutive prime factors)
1 is prime...
seems to be only 11 powers of ten that are products of two integers without
any zero digits:
theorem states that the area of the central hexagonal region
determined by trisection of each side of any triangle ABC and connecting
the corresponding points with the opposite vertex is exactly one
tenth (1/10) the area of the whole triangle ABC.
people argue that we only use 10% of our brains... No, this is
wrong: while the majority of the brain may not be active at any
one moment, all of it is essential for normal function. See mythical
most advertisements, including newspapers, the time displayed
on a watch is approximately 10:10.
The reason for this is to "frame" the logo of the watch
maker. The hands at that number cause the eyes to look right at
the logo! - posted
by Shaun Hussey, Graphic Designer
The hands on the dial indicating 10:10 also represent a smiling
face, sells better than watches indicating e.g. 08:20. - posted
father is better at caring for ten children
than ten children are for one father".
ten lists are very recurrent. The first top ten to
do and to not do list was perhaps the "Ten Commandments
of God" given to Moses. The Top-Ten lists usually are:
Top Ten To Do, Top Ten Jokes, Top Ten Reasons, Top Ten Links/Websites,
Top Ten Music/Songs, Top Ten Movies, Top Ten Headlines, Top
Ten Mistakes, Late Show Top Ten, Top Ten Reviews/Lists, Tot
Ten Inventions of the Century, and... Top Ten Numbers!
Sunday, October 10, 2010. This occurrence is special because
the first two numbers added together equal the first two digits
of the year: 10/10/2010 > 10 + 10 = 20.
Such dates occur every 201 years, the previous one was 09/09/1809
and the next one will be 11/11/2211. In China, the number ten
has a special place as it symbolises 'perfection' in almost everything.
Hence 10/10/10 becomes a special day for the Chinese. In fact,
many people in China are planning their wedding on this auspicious
hexagram of the I-Ching: Lü (履)/
Heaven above, the lake below:
The image of TREADING.
Thus the superior man discriminates
between high and low,
And thereby fortifies the thinking of the people.
different languages (© G.
(Old English tēn, tīen)
| *DEKM(T) |
Sanskrit | DASA |
Greek, Attic | ΔEKA deka |
Latin | DECEM |
French dix; Spanish diez;
Portuguese dez; Catalan déu;
Provençal dètz; Romanian zese;
Rumansh diesch; Sardinian dèche.
Germanic | TEHUN |
German zehn; Danish and Norwegian ti;
Swedish tio; Icelandic tíu.
Slavic | DESETI |
|Russian десять desyat';
Czech and Slovenian deset;
script' to modern sinograph 十 :
Old Chinese (pron.) | zhyep |
|Chinese 十 shí.
The sinograph 拾 is used as a replacement for 十 to
prevent forgery on legal and financial documents.
root | '-S-R |
Ancient Egyptian [mḏ-] met;
|Arabic عَشَرة 'ashra;
Hebrew עשר éser;
Maltese: għaxra; Amharic asir (pron.
The roots of the word ten are hidden
in the following words: DECI-, DECIMAL, DECIMATE, DECUPLE,
DECURION, DICKER, DIME; DECEMBER, DECEMVIR, DECENNARY, DECENNIUM,
DECUSSATE; DENARIUS, DENARY, DENIER; DEAN, DECA-, DECADE, DOYEN;
DECAGON, DECALOGUE, DECAMERON, DECAPOD; TENTH, TITHE. German:
DECHANT, DEKAN, -ZIG. French: DENIER, DENRÉE, DÎME.
Italian: DANAIO. DERRATA (< denarata).
the third honest number, because
11 = "two plus nine".
is the only palindromic prime with an even number of digits.
is the smallest prime with multiplicative and
additive persistence of 1.
+ 5 = 62 - 52
= LV/V = CX/X = DL/L = MC/C --
power of 11 ends in a 1.
12x9+3 = 111
123x9+4 = 1,111
1234x9+5 = 11,111
12,345x9+6 = 111,111
123,456x9+7 = 1,111,111
1,234,567x9+8 = 11,111,111
12,345,678x9+9 = 111,111,111
123,456,789x9+10 = 1,111,111,111
two embedded elevens.
on a calculator, the number 11 reads the same whether the calculator
is turned upside down or reflected on a mirror, or both.
large number is divisible by 11 if the difference between the sum
of its odd position digits (units, hundreds, etc.) and the sum
of its even position digits (tens, thousands, etc.) is 0 or a number
divisible by 11.
Another neat method to test for divisibility by 11 works by repeatedly
subtracting the last digit from the remaining digits:
5915 - 8 = 5907; 590 - 7 = 583; 58 - 3 = 55; 5 - 5 = 0
If this process results in 0, the original number is divisible
by 11, and the sequence of last digits gives the quotient. In this
case, the last digits are 8, 7, 3 and 5, so 59158/11 = 5378.
AB + BA, ABBA and ABCABC are
all multiple of 11 (A, B and C are digits, zero included).
11 = 65 + 56 (palindromic equality)
112 x 9182736455463728191
posted by Yosuke Ikeda, Yasuji Kondo, Yasuhiko Sakaitani, Ken Hirotomi,
Hiroyuki Ozaki, Atushi Tanaka, Ryohei Miyadera (Kwansei Gakuin
65 + 56, and 652 – 562 = (3 x 11)2,
112 = 30 + 31 + 32 +
33 + 34 (sum of consecutive
powers of 3)
113 = 32 + 192 + 312
11 = 0.09 09 …
2 / 11 = 0.18 18 …
3 / 11 = 0.27 27 …
4 / 11 = 0.36 36 …
5 / 11 = 0.45 45 …
6 / 11 = 0.54 54 …
1.1 = 11 x 1.1
triangle with a constant of 11;
2 + 3 + 6 = 2 + 5 + 4 = 6 + 1 + 4 = 11
plus two' is the anagram of 'twelve plus one'.
Maoris, the initial inhabitants of New Zealand, used for reckoning
or accounting purposes the undecimal (base-11) positional notation
Swiss town of Solothurn has
a special affinity with the number 11. This number is everywhere
in the city: there are 11 museums, chapels and churches, as well
as eleven historical fountains and eleven towers, and a clock
with a dial that only shows 11 hours. There are also some interesting
facts about the presence of the number 11 on the city’s
landmark, the Cathedral of St. Ursus. It took 11 years to build
it (1762-1773), the facade is 3 x 11 meters high, the tower measures
6 x 11 meters up to the weathercock; the stairs in front of the
cathedral have levels between every eleven steps. The inhabitants
of Solothurn even call their local beer "Öufi-Bier" (eleven-ale)
in German. The Canton of Solothurn was the eleventh to become
part of the Swiss Confederation.
one dollar coin (commonly called "Loonie")
is a 11-sided gold-coloured coin.
If your attention has been drawn to clocks and watches at exactly
11:11, 12:12, 10:10, 22:22, 12:34, 2:22, 3:33, 4:44 or 5:55, then
you are a 11:11-phenomenon
addict... In fact, some people believe that when they notice
the number pattern 1111 or the digits 11:11 on digital time pieces,
time/temperature signs, and so on, that there is an underlying
reason besides mere chance or coincidence. A belief of this nature
is related to the idea of synchronicity.
The date ‘November 11th, 2011’ has three 11’s
aligned for the first time in a century.
the perfect palindromic day, is being considered lucky by many,
as couples all over the world are planning to get into wedlock
on this date.
November 11th, 2011, at 48 minutes and 47 8/9 seconds before
Noon the time will be:
11/11/11 11:11:11.1111111111111... -- Bob Morris
which are already significant to us, such as calendar dates that
also coincidentally fall into an obvious pattern, become doubly
significant. It is known that the human brain is hard-wired to
look for meaningful patterns in the sensory data it collects
from the world. The fact that the date 11/11/11 appears important
to some people, teaches us that human nature is cognitively prone
to find ‘significance’ in coincidences.
An average room holds 11 x 100 pounds of air!
According to Dr
Michio Kaku our universe is a four-dimensional ball floating
in eleven dimensions.
to a survey of Graham Waters, Tuesday morning at 11:45 AM
is the most stressful time of the working week.
the most boring day of the 20th century was 11 April
1954. The date was discovered after 300 million facts were fed
into a new computer search engine in Cambridge called "True
the word in the English language that contains the letters to
form the most numbers. With its letters it is possible to spell 11
numbers: three, eight, nine, ten, thirteen, thirty,
thirty-nine, eighty, eighty-nine, ninety, and ninety-eight.
11 is used to check the 8-digit
ISSN (International Standard Serial Number for periodicals
number 11 is a favorite of gamblers - particularly blackjack
and Keno players.
between the divine numbers 10 and 12, the number 11 was, according
to Medieval numerologists, pure evil, and represented sinners.
million seconds is 11 days and a half.
French numeral onze (= eleven) was
also an old French slang term meaning 'a pair of legs' (1833).
a fictional term for the fear of palindromes, which is a palindrome
itself and contains 11 letters. The term is
a piece of computer humor entered into the 1981 "The Devil's
different languages (© G.
(Old English endleofon)
| *OINDEKM(T) |
Sanskrit | ekādaśa |
Greek, Attic | 'ENΔEKA héndéka |
Latin | VNDECIM |
French, Portuguese, Catalan, and Provençal onze;
Spanish once; Romanian un-spre-zese;
Rumansh endisch; Sardinian úndagi.
Germanic | AINLIF (means 'one left over')
and German elf; Danish and Norwegian elleve;
Swedish elva; Icelandic ellefu.
Slavic | JEDINU NA DESETJE |
|Russian оди́ннадцать odinnadtsat';
Czech jedenáct; Slovenian enajst;
|Chinese 十一 shíyī.
Egyptian metwie; Akkadian ishteshsheret.
|Arabic إحدى عشر ahada‘ashar;
Hebrew אחד עשר ahat'esrei;
Maltese: ħdax; Amharic asra-and.
The roots of the word eleven are hidden
in the following words: UNDECUMANI, Roman soldiers from the
eleventh Legion; UNDECIREMIS, an ancient Greek or Roman war
galley with eleven banks of oars; UNDECAGON, UNDECILLION. Italian:
Number (11) here.
is the smallest number with exactly six divisors, and the smallest abundant
is the largest known even number expressible as the sum of two
primes in one way (5 + 7).
/ (1 + (1 / (1 + 1/5)))
= (0! + 0! + 0!)! x (0! + 0!)
24 - 22
= 31 + 32
= 42 - 41
1122334455667789 = 161616161616161616 (periodic
posted by Yosuke Ikeda, Yasuji Kondo, Yasuhiko Sakaitani, Ken
Hirotomi, Hiroyuki Ozaki, Atushi Tanaka, Ryohei Miyadera (Kwansei
Gakuin High School) -
= 73 + 103 - 113
122 = 103 - 83 - 73 -
123 = 93 + 103 - 13
125 = 45 + 55 + 65 +
75 + 95 + 115
1/152 + 1/202 (smallest
integers of the reciprocal
12 = 144 is palindromic to
441 = 21 x 21
12 x 12 + 21 x 21 = 585 is also palindromic
other curious palindromic equalities involving 12:
12 x 42 = 24 x 21
12 x 63 = 36 x 21
12 x 84 = 48 x 21
12 + 21 =
3 + 4 + 5 + 6 + 7 + 8
+ 34567 is prime.
32 + 3 = 111
400/33 = 12.1212121212...
are 12 primary ways of arranging 8 queens on a chessboard so
that no queen can capture any other queen.
+ eleven = twoeleven, twOelEveN - ONE =
the symbols of the phone dial.
Telephone Number Mnemonics
American visitors are familiar with an ingenious method of making
telephone numbers more memorable. In the US many companies advertise
their telephone numbers with words. For example "Call 1800-DOG-HELP" might
be the advertising slogan for a dog rescue center. This is much
easier to remember than "Call 1800-364-4357".
To aid this system, the buttons on telephones are marked with letters,
as shown on the right. This method has been used in Britain too,
although it is now far less popular.
is correct: 12 Midnight A.M. or 12 Midnight
12 midnight A.M. and 12 midnight P.M., or 00:00 A.M. and 00:00
P.M., mean nothing at all. They are simply the midpoints that divide
the day into two equal halves.
Each and every day begins exactly at midnight, and each A.M. begins
precisely thereafter. Similarly, each P.M. begins immediately after
noon. No meaning can be assigned to 12:00 A.M. (00:00 A.M.), or
to 12:00 P.M. (00:00 P.M.). They are merely reference points meant
to simplify timetables for us.
A dozen is
a group or set of 12: a dozen bottles
A shock is
a group of 12 sheaves of grain stacked upright
in a field for drying. The word shock means also a lot consisting
of 60 pieces; -- a term applied in some Baltic ports to loose
consists of twelve persons chosen to decide
who has the better lawyer. -- Robert
21 | 12 | 2012
2012 is claimed by some to be a great
year of spiritual transformation (or apocalypse). Many esoteric
sources interpret the completion of the 13th B'ak'tun
cycle in the 'Long Count' of the Maya calendar (which occurs
on December 21 by the most widely held correlation) to mean there
will be a major change in world order.
different languages (© G.
(Old English twelfe)
| *DWÔDEKM(T) |
Sanskrit | dvādaśa |
Greek, Attic | ΔΩΔEKA dódéka |
Latin | DVODECIM |
French douze; Spanish doce;
Portuguese doze; Catalan and Provençal dotze;
Romanian doi-spre-zese; Rumansh dudisch;
Germanic | TWALIF (means 'two left over')
German zwölf; Danish, Norwegian,
and Swedish tolv; Icelandic tólf.
Slavic | DVANADESETJE |
|Russian дванадцать dvënadtsat';
Czech dvanáct; Slovenian dvanajst;
|Chinese 十二 shí'èr.
Egyptian metsn'wse; Akkadian shinsher(et).
|Arabic إثنا عشر ithna'ashar;
Hebrew שנים-עשר shteim'esrei;
Maltese: tnax; Amharic asra-hulet.
The roots of the word twelve are hidden
in the following words: DUODECILLION, DUODECIMAL, DUODENAL,
DUODENARY, DUODENUM; DODECAGON, DODECAHEDRON, DODECANESE, DODECAPHONIC;
DOZEN; TWELVEMO. French: DOUZAINE. Italian: DODICENNE, DOZZINA.
0-6 | 7-12 | 13-23 | 24-69 | 70-200 | 201-684 | 5H0P
encouraged to expand and/or improve the number facts featured
on this page. Send
us your comments, feedback or suggestions.
You can use any of our content (pictures, texts) in your non-commercial
web page for free as long as you leave the copyright and author's info intact
and link to us.
work is licensed under a Creative
Commons Attribution - NonCommercial - ShareAlike 2.5 License.
1. We always credit our sources, when we can.
2. Some of the material on this web section is submitted by our
readers/visitors. Where cited, excerpts are quoted or italicized,
and authorship credit is prominently supplied.
3. Most authors/submitters, however, prefer to remain anonymous,
for reasons of their own, and we respect their wishes.
4. If you believe you have identified material on this web site
that has not proper permission (and can provide us with verifiable
proof of ownership), or that should (but does not) credit a verifiable
source, please bring it to our
5. Any oversights, omissions and corrections will be updated as
soon as possible.
of Numbers © G. Sarcone, Archimedes Lab,