We never said we had 3 or any number of bombs. We wanted the Japs to think we could nuke every major city till the cows came home. They probably thought Tokyo was next. I am suprised they didn't surrender sooner.
As far as the number killed, the US killed more German civillians in a single carpet bombing then both nukes combined.
Why invade Japan? It was a war. You keep going until someone surrenders or you destroy your enemy. Not at all like today where you don't even need to declare war.
