Maths Magic: Number Game, How Old?

Give the following Instructions to a person:

1. Write down your age(or any number)
2. Multiply it by 3.
3. Add 1 to the total.
4. Multiply by 3.
5. Then add the original number(age) to the total.

Then ask him the resulting
 number and you take away the last digit.
This gives you the Original Number(Age). Try now :)