Stupid math tricks (idea)

Number Transformation:

1. Pick any number.
2. Add 3.
3. Multiply your result by 10.
4. Multiply your result by your original number.
5. Subtract 10.
6. Divide by 10.
7. Add 1.
8. Divide by your original number.
9. Subtract 3 from the number
10. Subtract your original number.

The result is always 0 (zero).

1. Pick a number between 1 and 9.
2. Multiply this number by 2.
3. Add 5.
4. Multiply by 50.
5. If you have already had your birthday this year, add 1750*. If you haven't had your birthday yet, add 1749*.
6. Last step: Subtract the four digit year that you were born.

The first digit of the answer is the original number you chose. The remaining two digits represent your age.

*: given for the year 2000. Increase these values by one for each successive year.

Prime number trick

1. Choose any prime number greater than 3
2. Square that number
3. Add 14
4. Divide by 12

The remainder will always be 3.

Finding someone's age

1. Ask the person to multiply the first number of his or her age by 5.
2. Tell them to add 3.
3. Now tell them to double this figure.
4. Finally, have the person add the second number of his or her age to the figure and have them tell you their answer.
5. Deduct 6 and you will have their age.