Telephone Math

Can you figure out why this works?

1. Type into a calculator the first 3 digits of your phone number (not the area code--your prefix)

2. Multiply by 80

3. Add 1

4. Multiply by 250

5. Add the last 4 digits of your phone number

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

7. Subtract 250

8. Divide by 2

Is this your phone number?