How people figure stuff like this out? And yes, I tried it, it works for me.
Grab a calculator (you won't be able to do this one in your head).
1. Key in the first 3 digits of your work DIRECT landline phone number at WORK (NOT the area code).
2. Multiply by 80
3. Add 1
4. Multiply by 250
5. Add the last 4 digits of your work phone number
6. Add the last 4 digits of your work phone number again
7. Subtract 250
8. Divide by 2
DO YOU RECOGNISE THE NUMBER?