Try this on yourself & then on your friends.

1. Open the calculator on your phone.

2. Take your age and multiply it by 2.

3. Add 5.

4. Multiply by 50.

5. Subtract 365.

6. Count loose change in your pocket* add to current total.
     (*Must be between 0 and 99 cents). 

7. Add 115.

   The first two digits = Your Age.
   The last two digits = The Amount of Change in Your Pocket.

    Now Go Have A Little Fun With Your Friends...

Here's another fun one.

1. Have someone open the calculator on their phone.

2. Ask them to think of any 3-digit number, but don't tell you what it is.

3. Have them to enter that 3-digit number twice.
    For example: If they are thinking of 273, they should enter 273273 into the calculator.

4. Pretend to focus on what they are thinking for a moment... Then say "Divide your 6-digit number by 7.

5. Again, pretend to focus on what they are thinking for a moment... Then say "Divide your 6-digit number by 11.

6. Again, pretend to focus on what they are thinking for a moment... Then say "Divide your 6-digit number by 13.

    Now tell them "If I did my mental math right I should have brought you back to your original 3-digit number.