Interesting Maths Facts


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  • Notches (cuts or indentation) on animal bones prove that humans have been doing mathematics since around 30,000 BC.
  • Ancient Greeks used little rocks to represent numbers. The name of Calculus means pebbles in Greek.
  • The = sign (“equals sign”) was invented by 16th Century Welsh mathematician Robert Recorde, who was fed up with writing “is equal to” in his equations.
  • The word hundred is derived from the word “hundrath”, which actually means 120 and not 100.
  • Zero (0) is the only number which cannot be represented by Roman numerals.
  • Many Chinese hospitals do not have a 4th floor  because the words four in Japanese, Cantonese, Mandarin and Korean (shi, sei, si, sa) sound the same as the words in those languages for death.
  • Forty is the only number with letters in alphabetical order, while one is the only one with letters in reverse order.
  • The number 5 is pronounced as ‘Ha‘ in Thai language. 555 is also used by some as slang for ‘HaHaHa’.
  • Zero is an even number. Mathematicians remember it. Many people take longer to decide whether it is even or odd.


Mathematical Beauty

e + 1 = 0

Euler’s identity is often cited as an example of deep mathematical beauty.

Constance Reid: Euler’s identity is “the most famous formula in all mathematics”.

Euler’s Identity is a special case of his formula from complex analysis suggested by Swiss mathematician Euler in  1748.

The identity links five fundamental mathematical constants:

  • The number 0
  • The number 1
  • The number π (π = 3.141 . . .)
  • The number e (e = 2.718 . . .)
  • The number i, the imaginary unit of the complex numbers.

Euler’s Identity “is absolutely paradoxical; we cannot understand it, and we don’t know what it means, but we have proved it, and therefore we know it must be the truth”. – Benjamin Peirce.


We Lack Numeracy Skills

Alan Smith reported amazing statistics of adult numeracy:

2011 England Survey: 49 of 100 adults lacked of numeracy Level 1 skills (fractions, percentage, and decimals).  The figure is only shocking for 51% of population.

OECD reported (PIAACX2012) that forty percent of USA young people aged 16-19 were below Level 2.

This is statistics. Statistics is a part of mathematics and it is about us as a group.

There are two categories of people who can and who cannot do numbers.

Are You in a category of people who are comfortable with numbers? Check / train yourself at the website A+Click

Pythagorean Triples Were Known 1,000 Years Before Pythagoras

The Babylonian clay tablet from the collection of Columbia University dating from 1,000 years before Pythagoras’s theorem is a trigonometric table which has 15 pairs of numbers forming Pythagorean triples: three whole numbers a, b and c:

a2 + b2 = c2

The tabet is known as the world’s oldest trig table. Babylonians used the base-60 numbers, which permitted many more accurate fractions than the contemporary base 10. For example, 2/3 = 0.6666… (or 40 minutes) was a finite number. The base-60 system were inspired from such shapes as a circle and the regular hexagon (see an example).

Mystic Number 7


Why we frequently use number 7?

Why there are seven days of week? seven deadly sins? seven wonders? . . . .

Look for the answer in the night sky or at

Why Is X The Unknown?

Terry Moore explains that the inventors of algebra were Arabic scientists. Their definition:

X = something, some undefined unknown thing = the unknown thing.

When the books were translated from Arabic to Spanish the Arabic unknown was “SH” that did not exist inSpanish. They replaced it by “X“.  It migrated to other European languages 600 years ago.

X is “X” because Spanish language does not have “SH“.

Cat, Rat, Hat, and Mat




Mary has a cat, and a rat, and a hat, and a mat.

If the cat is on the mat, and rat is in the hat, but the hat is on the mat, where is the rat?

This is a simple puzzle asked by Leslie Green, who collects dozens challenging puzzles.  The collection of Leslie Logic and Math Puzzles is presented at the website Aplusclick. It’s worth to try the challenging questions.