1. The Number 3 Trick
Take a number.
Double it.
Add 9.
Subtract 3.
Divide it by 2.
Subtract your original number.
Your answer should be 3.
Do the algebra to explain it:
Take a number: Let x = the number
Double it: 2x
Add 9: 2x + 9
Subtract 3: 2x + 6
Divide it by 2: x + 3
Subtract your original number: 3
That’s why your answer is 3.
2. The Number 4 Trick
The same basic trick also works with 4.
Take a number.
Double it.
Add 12.
Subtract—the remarkable 4.
Divide it by 2.
Subtract your original number.
Your answer should be 4.
Do the algebra to explain it…
3. The Number 5 Trick
Ask somebody to think of a number and keep it secret.
Then ask that person to double the secret number and then multiply it by 5.
Ask for the total.
Whatever the total is, knock off the last digit and you will have the secret number the person mentally chose at the start.
4. The Number 37 Trick
There is a three-factor in this one.
Multiply 37 by 3, and you have 111.
Jump up three numbers to 6, and mutliply by 37 again.
You have 222.
Three more and you are at 9.
Multiply by 37 again and you have 333.
This “jump-up-three” routine works all the way up to 27
(27 x 37 = 999).
After that, 37 loses its magic.
5. “The Best Year Of Your Life” Number Game
Write down the year in which you were born.
Write down an important year during your life-time.
Next, write down the number of years that have elapsed since that important year.
Put down your age this year on your birthday.
Add up the numbers on your list.
Divide it by 2.
If your mental computer is working, you should have the current calendar year.
6. Recurring Number
Write down the following 8-digit number on a piece of paper: 1 2 3 4 5 6 7 9
Ask a participant to circle one of the digits.
Example : the participant circles number 7.
Now ask the participant to multiply the 8-digit number by 63.
A magic result happens :
1 2 3 4 5 6 7 9 x 6 3 = 7 7 7 7 7 7 7 7 7
The answer is a row of the chosen number 7.
How to do this maths trick:
When the participant circles a number, you need to multiply the chosen number by 9.
Example: if 3 was chosen you would multiply 3 x 9 = 27.
Then you would ask the participant to multiply the 8-digit number by the number you obtained (27)
Therefore, multiply 12345679 by 27 and you magically get the answer 333333333.
Einstein would be proud!
