A friend just sent this to me in an email, and I thought it was so neat I had to share. I've tried to figure out how it works, but it's beyond me. Quite amazing though. The phone numbers here in the UK, after you take away the area codes, have six digits remaining, and this works with those. So wherever you are in the world, for the purpose of this exercise you need to assume that your area code is all the digits up to the last six in your phone number. I just tested it with a 7 figure phone number, and it didn't work, so you need to use the last six digits of your phone number.
Here it is:
1. Grab a calculator. (You won't be able to do this one in your head)
2. Key in the first three digits of your phone number (NOT the area code)
3. Multiply by 8
4. Add 1
5. Multiply by 250
6. Add the last 3 digits of your phone number
7. Add the last 3 digits of your phone number again.
8. Subtract 250
9. Divide number by 2
Do you recognize the answer?