Math Class Crush?

Do you have a crush on someone in your math class at school? Well my Dad was showing me this video here and I got an idea! So your dying to get your crushes phone number? Here's a sneaky way to do it (assuming they type in the correct numbers):

1. Grab a calculator
2. Tell your crush to type in the first 3 digits of their phone number (NOT their area code) then multiply it by 80.
3. Either have them give the calculator back or let them keep and have them do the rest.
4. Add 1 to that
5. Multiply by 250
6. Have them add the last four digits of their #
7. Add the last four digits again
8. Subtract 250
9. Divide by 2
10. And then you have their phone #! MAGIC!

Or I suppose you could just ask them for it... :/ But how creative is that? ;)