First of all I think we need to know the first term and common difference."Arithmatic progression, if i know how many numbers there are, their sum?":

With that we could tell you the formula, but I think its better you consult your text book. Text books generally have a flow that makes it easy to understand, remember and apply.

I am sorry, this could be hard. I have no idea of this."and their product?"

I think its better if you post a problem that demands the use of these formulae. Can you post one?

Afterthought: I think you have a problem at hand and thus you want to know the formulae. So could you post those exactly as in the question?"and Geometric progression, if i know the second term and the sum to infinity?"