Tricks and Trivia

### Tricks

Who is Charles Dodgson Finger Math
Babbage invented whatMultiplying 2 digit numbers
Other Useful Math Trivia

Tricks

Finger Math

Multiplying by 9

Hold out your hands in front of you so that your thumbs point toward one another.

Visualize that your left pinky finger represents 1, the next finger 2, and so on left to right, until your right pinky finger represents 10. Those fingers represent the number you wish to multiply by 9. To do so, simply put the finger down you wish to multiply by 9. All fingers to the left of the down finger represent the tens digit of the answer while all fingers to the right represent the ones digit.

Example: 6 x 9. Put the finger representing 6 down (the right hand thumb). To the left of the down finger, you have 5 fingers up. That's your tens digit. 5. To the right, you have 4 fingers up. There's your ones digit. 4. Put those together and you have your answer: 54.

Edward Julius in his book Rapid Math Tricks And Tips explains how to add numbers faster.

Here is how to rapidly add numbers.

1+9+2+8+4+5+6+5+3+7=

1+9=10 2+8=10 4+6=10 5+5=10 3+7=10

Think 10, 10, 10, 10, and 10

Here is another example

3+8+7+1+1+4+5+6+2=

3+8=11

7+1+1=9+11=20

4+6=10

20+10=30

5 and 2 are left so add 5+2 and get 7 and add that to the 30

Multiplying 2 digit numbers

Edward Julius in his book Rapid Math Tricks And Tips explains how to multiply numbers faster.

Here is an easy way to multiply 2 digit numbers by 2 digit numbers.

Step 1 Multiply the ones digit together

Step 3 Multiply the tens digit together

Step 1 Choose two numbers

Step 2 Form a Fibonacci sequence for ten numbers

Example, I choose number 5 for my first number and 6 for my second number.

Then I add the numbers to get a Fibonacci sequence. 5+6 gives my 3rd number which is 11; 6+11 gives me my 4th number which is 17. The entire sequence is as follows:

1st - 5
2nd - 6
3rd - 11
4th - 17
5th - 28
6th - 45
7th - 73
8th - 118
9th - 191
10th - 309

The trick is to multiply the 7th number by 11 (you always multiply it by 11). The answer you get when you multiply the 7thnumber by 11 will always be the same result as if you had added all ten numbers. In the above example, the 7th number is 73. Multiply 73 by 11 and the answer is 803. If you add all 10 numbers together the answer will also be 803.

Try this with your own numbers.

Trivia

Charles Babbage was very interesting. He was born in 1791. He developed the blueprint for the modern computer, the cow catcher, and he even discovered how to find out how old a tree is by counting the rings. He said it was possible to determine the climate by examining the rings on a tree by seeing how big they were. Charles Babbage was a mathematician.

Did you know the mathematician Charles L. Dodgson who invented the doublets game was known as Lewis Carroll (author of Alice in Wonderland) ? To play the
doublets game .

Do you know the name of some of the numbers? Well, here they are:
 million 106 billion 10 9 trillion 1012 quadrillion 10 15 quintillion 1018 sextillion 1021 septillion 1024 octillion 1027 nonillion 1030 decillion 1033 undecillion 1036 duodecillion 1039 tredecillion 1042 quatuordecillion 1045 quindecillion 1048 sexdecillion 1048 septendecillion 1054 octodecillion 1057 novemdecillion 1060 vigintillion 1063 googol 0100 googolplex 10googol = 1010100

Did you know Pascal invented the first adding machine and it was called Pascaline?

Here are all the different kinds of numbers. Do you know them all?

Other Useful Math Trivia

Here are some other useful ways of remembering some mathmaticial operations.

Perimeter: the word rim will help you remember that perimeter measures the distance around the rim of an object.

The number of teaspoons in a tablespoon: There are 3 teaspoons in 1 tablespoon. Remember that both teaspoon and tablespoon start with the letter "t" and the word three rhymes with t.

The order of operations in long division: Remember the phrase "Did my sister bring rabbits?"

 Did Divide My Multiply Sister Subtract Bring Bring Down Rabbits Remainder

A way to remember the order of mathematical operations is to remember the following phrase "Please Exercise My Dear Alligator Sal."

 Please Parentheses Exercise Exponents My Multiplication Dear Division Alligator Addition Sal Subtraction