Math Symbols

We use math symbols to express complex mathematical texts in a shorter form.

=   replaces   “is equal to

+ replaces “and

×   replaces   “multiplied by

. . . .

There are many Greek symbols like   π ∑   and special symbols like   √ ∞ ∈   in mathematics.

John David Walters explains where math symbols come from in the video:

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A Self-educated Mathematician Established the Boolean Algebra

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George Boole (1815–1864)

The term “Boolean algebra” honors George Boole (1815–1864), a self-educated English mathematician. Boolean algebra captures essential properties of both set operations and logic operations. Boolean logic is credited with laying the foundations for the information age (computers and cell phones).

One of the puzzles on Boolean logic:

There are three balls X, Y and Z. They are colored red, white and blue, but not necessarily in this order. One, but only one, of the following statements is true:

X is red

Y is not red

Z is not blue

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How many solutions does the puzzle have?

Think yourself before checking the solution.

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.

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

APLUSCLICK.ORG is online

To respond to growing demand of international users, we redirect http://www.aplusclick.com to the new free website www.aplusclick.org . All links  for extension .com are the same for extention .org  Now the site is hosted in Switzerland. Please update your links. Happy challenges at www.aplusclick.org

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Cat, Rat, Hat, and Mat

 

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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.

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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?

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Leslie Green gives the answer : 96 days.

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