The wonder of Maths..

I wonder how the creator of this work this out?

1) Key-in the first 4 digit of your handphone number into the calculator
2) multiply by 80
3) add 1
4) multiply by 250
5) plus last four digit of phone number
6) plus last four digit of phone number again
7) minus 250
8) divide by 2

Is the answer your handphone number????

AMAZING, right~!!!!!

Cheers~!!