Maths trick

[rebbonk]

1. Grab a calculator. (You won't be able to do this one in your head)
2. Key in the first three digits of your home phone number (NOT the area code)
3. Multiply by 8
4. Add 1
5. Multiply by 250
6. Add the last 3 digits of your phone number
7. Add the last 3 digits of your phone number again.
8. Subtract 250
9. Divide number by 2
Do you recognize the answer?

Perhaps some people have too much time on their hands?