1. Grab a calculator (you won't be able to do this one in your head)
(first of all, let me say I'm insulted by that. I tried and I did this in my head without any problem, though it certainly took longer)
2. Key in the first three digits of your phone number (NOT the area code)
(second, let me say this is also ridiculous. It works fine with the area code. It's just a less interesting answer)
3. Multiply by 80
4. Add 1
5. Multiply by 250
6. Add the last 4 digits of your phone number
7. Add the last 4 digits of your phone number again.
8. Subtract 250
9. Divide number by 2
Do you recognize the answer?
So yeah, it's cool. And I'll never figure out how people work these things out. I've tried to create similar "tricks" but have never been able to do it. It irritates me that other people are so much smarter than me, and it's unfair that it irritates me. I should get over myself. I'm not all that, and I know that, I just wish I were! :)