This is a bit irrelevant but BIN LADEN IS DEAD?!
And to everyone else, the rule for fancy goldfish is 20 gallons for the first fish and an additional 10 gallons for every extra fish.
The rule for common goldfish is still a bit obscure, although I'd say you could keep 1 or 2 in a 50 gallon. Some common goldfish grow gigantic, some don't, it all depends on their first 120 days as fry. If they are taken care of really well and kept in clean water, the result will be a big goldfish.
It also depends on what you feed them. Sadly, our two goldfish passed away a couple of years ago but their life was rather spectacular. My mum won them at the fair and they went straight into a fish bowl. My parents found a gigantic tank in their attic and used it for the two goldfish. They then went on to add a decent filtration system and they took care of them like no ordinary goldfish (I wasn't born then; so I don't know whether this is entirely true!).
When I was about 3, I started to become quite interested in the goldfish. They were, at that time, 13 years old. My mum helped me feed them, but doing a water change on a 200 gallon fish tank isn't exactly recommended for a 3 year old
When I was, like, 7 I remember boasting at school about the age and size of my goldfish (cus I was cool like that lol)
From the age of ten onwards, I started to take care of the tank: 50% water changes weekly, algae scrub, filter clean etc. I fed them a really balanced diet, always eager to go to the aquatic shop and buy them bloodworms and brine shrimp for treats. We fed them peas, pellets, flakes, a really balanced diet.
Unfortunately, back then they were 20 and I didn't know they only had less than a year to live :(
I remember them being 14 inches long.