Thursday Thirteen - Numbers!

Sometimes, I just browse the internet aimlessly for the express purpose of stumbling upon something interesting that I would never have thought of to search. Today, I came upon numbers and followed that train of thought.

Here are 13 Interesting Facts About Numbers & Maths

1) 111,111,111 x 111,111,111 = 12,345,678,987,654,321.

2) 1234567.9 x 9 = 11111111

3) Multiply 37,037 by any single number (1-9), then multiply that number by 3. Every digit in the answer will be the same as that first single number.
For example: 37,037 x 5 = 185,185; 185,185 x 3 = 555,555

4) 2 is the only even prime.

5) 18 is the only number that is twice the sum of its digits.

6) 81 is the square of the sum of its digits.

7) 12+3-4+5+67+8+9=100

8) A Googol has 100 zeros.

9) 25 (5 x 5) is the smallest square that can be written as a sum of 2 squares
(3 x 3 + 4 x 4).

10) 40 is the only number whose letters are in alphabetical order.

11) 89 = 8^1 + 9^2 (What I mean is 8 to the power of 1 and 9 to the power of 2.)

12) Pi has been calculated to 2,260,321,363 digits. The billionth digit in Pi is 9.

13) This one is for people like me who can't remember their multiplication tables.

You can use your fingers for 1 x 9 to 9 x 9.

Hold both hands out in front of you, palms facing away. For 1 x 9, bend the little finger on your left hand. You're left with 9 fingers to the right of that little finger. Of course, you probably didn't need to use this method to get the answer to 1 x 9.

For 2 x 9, bend the ring finger on your left hand. Now there is 1 fingers to the left of the ring finger and 8 to the right of it. The answer is 18.

Jumping to 5 x 9. Bend your left thumb. Now you have 4 fingers to the left of your thumb and 5 to the right of it letting you know the answer is 45.

Its so much easier to explain if you could all just see my fingers! Try it out anyway :)