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


although it'* easy to do it with pencil and paper.

2. Key in the first three digits of your phone number (NOT YOUR 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?

Neat! And not overly obvious why it works.

first three digits * 80 * 250 with an offset of 250. 80 * 250 = 20000

this means first three digits multiplied by 2 and scooted over four decimal places. plus 250. add your last four digits twice, so you end up with your phone number times two with an offset of 250, subtract 250 = your phone number times two.

divide by two.

Heh, that'* awesome! And the sad part is, I totally forgot the last 4 digits of my home phone number! I think I need to call my parents more often