How much sperm does it take to make a baby?

It just takes one sperm cell to go into the female egg to then produce a baby

Actually, only one sperm gets fertilised and develops into a baby. But a lot more sperms are required to carry out reproduction. This is because it is not sure if one sperm definitely gets fertilised. Some weaker sperms perish. The strongest sperm among the numerous sperms get fertilised while the others perish.