0.999... = 1?

My stupid math prof tells me that .9999999... = 1. But I think he is just stupid.

So, what's your take?

Did you know that if you cut a sausage, you don't have a sausage anymore?  And if you try to make a sausage from successively smaller parts, you'll never finish.

So what I mean is, this topic is sausage.