Using a language with static typing means that there are a lot of tests you don't have to write. Do you remember the units trick from physics? If you forgot which equation you're supposed to use, keep on using identities until you're in the units you're supposed to be. Static typing checks that your units are correct for free.
Well, not entirely for "free", but I do agree that the price is much lower than what you end up paying eventually for the convenience of dynamic typing.
