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.


17 Best Puzzles of 2017


Aplusclcik team chose 17 Best Puzzles of 2017.

They are:

What country has the lowest birth rate in the World?


If certain words in this question are spelt wrong, how many of the eighteen words are spelt wrong?


A claustrophobic gentleman chooses his place in the train that will enter a tunnel just after the station. Where is the best place for him?2017Aplusclick3


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).

Formula of Love

Professional dancersLove is like π – natural, irrational, and very important.” – Lisa Hoffman

Certain scientists think that love is a chemical state of mind and the formula for love is as follows:

dopamine + seratonin + oxytocin

C8H11NO2 + C10H12N2O + C43H66N12O12S2 

How many atoms  are there in the formula of love?


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

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.




Selfie Math

Jim is going on a tour around the world. He has 5 tops, 4 bottoms, and 3 pairs of footwear. He wants to post a selfie everyday to show different places and his different outfits to his girl-friend Mary, who stays at home. He does not want to wear the same outfit twice. ## For how many days does he have enough clothing?


Leslie Green gives the answer : 96 days.

Can you explain why it is 96? What is logic behind?