Weird formula that yields a familiar number

Just got this via email. Can anyone explain how this works?

Here’s a math trick so unbelievable it will stump you. Grab a calculator (you won’t be able to do this one in your head.)

  1. Key in the first three digits of your phone number (NOT the area code).

  2. Multiply by 80.

  3. Add 1.

  4. Multiply by 250.

  5. Add the last four digits of your phone number.

  6. Add the last four digits of your phone number again.

  7. Subtract 250.

  8. Divide by 2.

And the answer is…

Not my phone number - there’s a digit missing*
*We have differently formatted phone numbers over here. But it does work for Aussiedopers if you change the first step to the first FOUR digits of your phone number :smiley:

We’ve done this before. I posted the mathematics behind it – it’s not very hard to see how this trick works.

For those interested (I know I was), here is that previous post Rysto referred to.

By the way Rysto, great explanation in that thread, thanks.

Thanks. I searched the SDMB for the phrase “area code” and it didn’t come up.