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.


The Largest Known Prime Number

The largest known prime number was discovered in 2016 by a computer laboratory of the University of Central Missouri .

257,885,161 – 1

is one of the Mersenne primes that can be written in form 2n – 1, where n is an integer.  They are named after 17-century French mathematician Marin Mersenne.


The number written in the decimal form contains 17 million digits.


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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?



2015 OECD PISA Global Education Survey

The top OECD countries were Singapore, Japan, Estonia, Finland and Canada. These countries also achieve high levels of performance and equity in education outcomes.


Source: OCDE

More than one in four students in Beijing-Shanghai-Jiangsu-Guangdong (China), Hong Kong (China), Singapore and Chinese Taipei are top-performing students in mathematics, a higher share than anywhere else.

Students in larger schools score higher in science and are more likely than students in smaller schools. Students in smaller schools reported a better disciplinary climate.

Gender gap: the share of top performers in science is larger among boys than among girls. Finland is the only country in which girls are more likely to be top performers than boys. Girls mostly seek positions in the health sector and boys  in becoming ICT professionals, scientists or engineers.

Five sample PISA Math questions:

  1. Cycling
  2. Numbers
  3. Many years ago
  4. Australia, Germany, and USA
  5. Math test score


Car Owner’s Puzzles

Can a specific subject provokes interest to Math?

For example, cars. How much does the gas cost in a month? What speed to choose? When do I need to change the tires? How to be on time? How much do I pay for a car during its life? . . .


What are other intersting subjects? Finance? Love? Sport?