Four is the only number that has the same number of letters as its meaning
F,O,U,R.

A number is divisible by 9 if the sum of the digits is divisible by 9.
9,18,27,36,45...

The number zero does not have its own Roman numeral
IX,XV,CM,VII...

Think to yourself 'How I wish I could calculate pi' and then count the letters in each of the words of that sentence. You now have a way of remembering the first seven digits of pi: 3.141592.
π

The first number to contain the letter a is 'one thousand'. See A NUMBER for the discussion behind this fact.
1,000

The only number to have its letters in alphabetical order is forty. See Alphanumbetical and try to think of other alphanumbetical mathematical words!
Forty

The numbers on opposite sides of a dice add up to seven.

There are more than 64 squares on a chess board. If you count the squares made up of multiple squares there are 204 altogether. There is one 8x8 square, four 7x7 squares, nine 6x6 squares, 16 5x5 squares, 25 4x4 squares, 36 3x3 squares, 49 2x2 squares and 64 1x1 squares.

A prime number has exactly two factors. Two is the only even prime number.
2

It should take no more than 20 moves to solve a Rubiks cube no matter which of the 43 quintillion possible starting positions you begin with.

A dodecahedron has twelve pentagonal sides.
.

A googol is one followed by one hundred zeros. This can be written as:
10¹⁰⁰.

Not many people appreciate (or understand) the mind-blowing fact that:
e^iπ = -1

Triangles, squares and hexagons are the only regular polygons that tessellate.



Check for yourself at the Tessellations page.

The equals sign was invented in 1557 by Welsh mathematician Robert Recorde. The word 'equal' is from the Latin word aequalis as meaning uniform, identical, or equal.
=

111111111 x 111111111 = 12345678987654321.

These two fractions add up to one and between them they contain all of the digits from nought to nine. It is the only way that this can be done.

Eight comes first if all the numbers are arranged alphabetically. What number would come last?
8

More numbers begin with the digit one than any other digit. This result has been found to apply to a wide variety of data sets, including electricity bills, street addresses, stock prices, population numbers, death rates, lengths of rivers and mathematical constants. This fact was famously attributed to physicist Frank Benford, who stated it in 1938, although it had been previously stated by Simon Newcomb in 1881.

Alice in Wonderland learns that in a class of 23 pupils the probability that two have the same birthday is more than a half. Alice is a fictional character created by author and mathemetician Lewis Carroll (1832-1898).

42 is the answer to the 'Ultimate Question of Life, the Universe, and Everything' according to 'The Hitchhiker's Guide to the Galaxy' created by Douglas Adams.

18 is the only number that is twice the sum of its digits.

Most clocks which have Roman numerals on their face use IIII for four instead of the more familiar IV.

.

There are currently over 7 billion people in the world and the number is growing very quickly. To see just how quickly have a look at our population counter.

Any number to the power zero is 1, and zero to any power is 0. The only unanswered question here is what is zero to the power zero?
0⁰

The Fibonacci sequence is a sequence of numbers where each term is the sum of the previous two terms. The first two terms are both one. The ratio of the n^th term to the next term gets closer to the golden ratio as n increases.

Air France, Iberia, Ryanair, AirTran, Continental Airlines, and Lufthansa don’t have a row 13 on their airlines because they are aware that many of their passengers consider 13 to be an unlucky number. Many office blocks, office buildings and hotels do not have a 13th floor for the same reason.

The following three consecutive numbers are the lowest that are divisible by cubes other than 1:

1375; 1376; 1377
(divisible by the cubes of 5, 2 and 3 respectively).

The digits of the number are the same as the digits of the power of ten in these cases:
1.3712885742 = 10^{0.13712885742}
237.5812087593 = 10^{2.375812087593}
3550.2601815865 = 10^{3.5502601815865}

The polar diameter of the Earth is quite close to (within 0.1%) half a billion inches.

The first time a digit repeats six times in succession in pi is at the 762nd position where you can find six nines in a row. This is known as the Feynman Point.

The term googol (a 1 followed by 100 zeroes) was first used by a 9- year old boy,Milton Sirotta, in 1938.

Trivia submitted by Paul Christian Sarmiento, Philippines

As weird as it may seem at first glance, f(x) = -1/(x+1) and g(x) = x/(x+1) have the same derivative.

Trivia submitted by Shiraz Dagia, Malawi

A number if multiply by 11 is just you bring down the last digits add the digit to the number on it's left and bring down the first number.
Example:
(15)(11)=---
Bring down 5
(15)(11)=--5
Then, 5+1=6
(15)(11)=-65
Last bring down the first digit which is 1
So,(15)(11)=165.

Trivia submitted by Jericho Fernandez, Laguna, Philippines

There is a number smaller than 'a thousand' or 'a hundred and one' with the letter a - it is any number like 0.001 or 'one thousandth' which is smaller than 101 or 1000. These decimals can get infinitely smaller so the proper term for the trivia should be that the smallest whole number not just the smallest number.

Trivia submitted by QA, Makaben

You can remember the value of Pi (3.1415926) by counting each word's letters in
'May I have a large container of coffee?'.

Trivia submitted by Ms. Prescott,

Trivia improves critical thinking.

Trivia submitted by Wisani, Gauteng, South Africa

A googolplex is a googol^{a googol}, or (10¹⁰⁰) to the power(10¹⁰⁰).

Trivia submitted by Anonymous, Planet Earth

40 when written in words "forty" is the only number with letters in alphabetical order, while one is the only one with letters in reverse order.

Trivia submitted by Dustin Joseph C. Manalo, Bulacan,Philippines

The number 0 is originally called cipher.

Trivia submitted by Paras, Philipines

The billionth digit of Pi (3.1415 ...) is 9.

Trivia submitted by Joy, Manila, Philippines

What is the correct mathematical name of the division bar in a fraction? The answer is VINCULUM.

Trivia submitted by Lovely Tinam-isan, Muntinlupa, Philippines

The term "jiffy" is an actual unit of time which is the 1/100th of a second.

Trivia submitted by Josh Anilov C. Funelas, Manila, Philippines

The value of zero was first used by the ancient Indian mathematician Aryabhata.

Trivia submitted by Wency Orbina, Philippines

2520 is the smallest number that is divisible by 1,2,3,4,5,6,7,8,9 and 10.

Trivia submitted by MathWizard, Phillipines

Moving each letter of the word 'yes' 16 places further up the alphabet produces the word 'oui', the French for 'yes'.

Trivia submitted by Greg Ross, Futility Closet

Forty-two percent of Slovenian two-year-olds know the number two, while only four percent of English two-year-olds do.

Trivia submitted by Francie Diep, Popular Science

The word 'twelve' is worth 12 points in Scrabble. .

Trivia submitted by Greg Ross, Futility Closet

The words 'ace, two, three, four, five, six, seven, eight, nine, ten, jack, queen, king' contain 52 letters. There are 52 cards in a pack (excluding jokers).

Trivia submitted by Greg Ross, Futility Closet

If you square11111111 the answer would be 123456787654321. (count the number of 1s and that's the middle number).

Trivia submitted by Ranz Louie Ricasa, Philippines

The polygon with 1000000 sides is called megagon.

Trivia submitted by Ranz Louie Ricasa, Philippines

99*99=9801
999*999=998001
9999*9999=99980001
99999*99999=9999800001.

Trivia submitted by Ranz Louie Ricasa, Philippines

If you find the difference between the number of edges and the number of faces of the tetrahedron, cube, octahedron and other solid shapes, the results will always be 2.

Trivia submitted by Ranz Louie Ricasa, Olongapo City,Philippines

The second hand on a clock is actually the minute hand.

Trivia submitted by Will, Northampton, England

If you write out pi to two decimal places, backwards it spells “pie”.
Found from buzzfeed.

Trivia submitted by Me, England

The Reuleaux Triangle is a shape of constant width, the simplest and best known such curve other than a circle.

Trivia submitted by Manuel Henryk Fabunan, Philippines