Magic Maths

This is quite an incredible math phenomenon.

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

1. Key in the first three digits of your phone number (NOT the Area code)
2. Multiply by 80
3. Add 1
4. Multiply by 250
5. Add to this the last 4 digits of your phone number
6. Add to this the last 4 digits of your phone number again.
7. Subtract 250
8. Divide number by 2

Recognise the answer ?