Expected Revenue %

I am trying to get another field like the Expected Revenue field which is Amount X Probability. I have made another $Amount field and a Percentage field and then made another Expected field which I just said to multiply Amount X Probability field but it is not making the probability field a %. So if I say amount is $100 X probability of 20 it's returning an answer of $2,000 instead of $20. How do I make it see the probability field as an actual %. Thought it would do that automatically since I made the field a % field. Thanks.