Fun With Numbers

I got this in an email and thought it's interesting enough to share.

1. Key in the first 3 digits of your phone number into a calculator (not the area code)
2. Multiply by 80
3. Add 1
4. Multiply by 250
5. Add the last four digits of your phone number
6. Add the last four digits of your phone number again
7. Subtract 250
8. Divide by 2 at last

And the answer is ...

your phone number ??