First of all, where did you get these numbers? it doesnt take billions of bad mutations, it takes as many mutations as it takes. If an organism has offspring that are all slightly mutated(and they are "bad mutations") they die off. The organisms with an advantageous or beneficial mutation live to reproduce, and their offspring carry that genetic mutation. Also, mutation isnt evolution. And it certainly isnt the only mechanism involved. Variation, for example, plays a huge role in evolution. Also, genetic isolation.
Now, if you want to bring statistics into the game, there's a few fundamental flaws in your argument. For one, just because the odds are stacked against something occuring, doesn't mean it won't occur, it also doesn't mean it won't occur again, repeatedly even. For example; what are the odds that I will become prime minister of Canada? There are some 32 million people in Canada. I have a one in 32 million chance of becoming prime minister, but does that mean i cant or won't? Of course not. (I might add that I have no ambition to become our prime minister.) As another example, think of a card game, any card game. You get a hand of cards. An ace, a queen, two fours and an 8. What are the odds that you would get that hand? phenomenal, but you still got that hand. Get over it, almost everything in the world that happens has phenomenal odds stacked against it, but IT STILL HAPPENS. Evolutionary scientists, anthropologists and biologists are way more educated and intelligent than you give them credit for, evolution has been tested and tested, it has been debated, it has been altered, shifted, rearranged and added on to. Despite people constantly opposing and trying to disprove evolution, it has survived over 100 years of scrutiny and guess what? IT IS STILL APPLICABLE, it solves more puzzles of life than any other theory before it, therefore, evolution is a true phenomenon, and until we find overwhelming evidence that another theory works, evolution is the explanation.