although there is no such evaluation tool in Excel 2011:Mac, you can still evaluate your formula in the formula bar in a way that we do in PC version, i.e. highlight the formula you want to evaluate in the formula bar, instead of pressing F9, you should press Command =
note: I am not 100% sure about the key combination as I don't have a Mac with me now. Let me know if you can't do it and I shall test it at home.