Try this...its really cool, only takes a minute *I'm not sure if this will work with European phone number, since there are 7 digits long)
1. Key in the first 3 digits of your phone number into a calculator (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 at last
Is it your phone number ??
If anyone tries to take my coffee I will hurl them into the fires of Mt. Doom!