How do i find my Mobilenumber on my Samsung Galaxy 5

I've been trying to give my friend my number. When I first got my *Samsung Galaxy S* I wrote it down in the memos: a mobile number that had 11 numbers in it. I can't remember where I got that from -- and now when I try to find it, I go into *About → phone-status*, but for phone number it says "unknown". I don't know what to do. If I click on the "unknown" thing it does nothing. I also thought numbers were meant to have 10 numbers. So how can I find out what my number is?