Phone Number Trick

1. Get a calculator. (You won't be able to do this one in your head)

2. Key in the first three digits of your phone number (NOT the area code)

3. Multiply by 80

4. Add 1

5. Multiply by 250

6. Add the last 4 digits of your phone number

7. Add the last 4 digits of your phone number again.

8. Subtract 250

9. Divide number by 2

Do you recognize the answer?

Explanation:

Let x= 1st three digits of phone number

let y= last 4 digits of phone number

x

80x

80x + 1

250(80x + 1) = 20000x + 250

20000x + 250 + y

20000x + 250 + 2y

20000x + 2y

10000x + y

This last step shows why you get your phone number back. x (which represents your first three digits of your phone number) is multiplied by 10000, which just moves it over 4 places and then y is put in the four places on the right.