Math Trick

I got this math trick via one of my forwarded email. Found it's very interesting, wonder how the origin person discover it. Salute, salute....

Let me share with you, in case you did not play this trick before:

1. Get a calculator

2. key in the first 3 digits of your phone number

3. Multiply by 80

4. Add 1

5. Multiply by 250

6. Add your last 4 digits of your phone number

7. Add your last 4 digits of your phone number again

8. Subtract 250

9. Divide number by 2

What is your result? Is the number familiar to you? Hehehe....don't you think the person who discover this very intelligent? Bravo to him/her!