How about telling the others how you found your account number?
I'll give it a go
Log in by putting your E-mail address and password in the two fields and then click on 'Profile' at the top right of the screen. You should then see something like this in the top of your browser:-
http://www.facebook.com/home.php#!/profile.php?id=1001880277In the above example, the number 1001880277 on the end is your account number
However, you do not use this number to log into facebook or to allow people to find you on facebook. The way to allow someone to find you on facebook if there are hundreds of other people with the same name as you, is to PM them the E-mail address connected to the account. Once they put that into the search box they will find you unless you have your privacy settings set so that you cannot be found
EDIT - Oooops! I shouldn't post with tired brain cell at 2:28am. Of course you can send the whole link including the number to a friend so that they can find you
