111,111,111

x

111,111,111

=

12,345,678,987,654,321.

x

111,111,111

=

12,345,678,987,654,321.

If you have a pizza with radius Z and thickness A, its volume is =

Pi*Z*Z*A

Pi*Z*Z*A

1089

x

9

=

9801.

x

9

=

9801.

Ancient Babylonians did math in base 60 instead of base 10. That's why we have 60 seconds in a minute and 360 degrees in a circle.

Students who chew gum have better math test scores than those who do not, a study found.

2,520 is the smallest number that can be exactly divided by all the numbers 1 to 10.

123 - 45 - 67 + 89 = 100.

123 + 4 - 5 + 67 - 89 = 100.

123 - 4 - 5 - 6 - 7 + 8 - 9 = 100.

1 + 23 - 4 + 5 + 6 + 78 - 9 = 100.

There are 177,147 ways to tie a tie, according to mathematicians.

In 1900, all the world's mathematical knowledge could be written in about 80 books; today it would fill more than 100,000 books.

The birthday paradox says that in a group of just 23 people, there's a 50% chance that at least two will have the same birthday.

Multiplying 21978 by 4 reverses the order of the numbers: 87912.

Isaac Newton's Principia Mathematica contained a simple calculation error that went unnoticed for 300 years.

2200 years ago, Eratosthenes estimated the Earth's circumference using math, without ever leaving Egypt. He was remarkably accurate. Christopher Columbus later studied him.

Mathematician Paul Erdos could calculate in his head, given a person's age, how many seconds they had lived, when he was just 4 years old.

Newton invented/discovered calculus in about the same amount of time the average student learns it.