Demps has a great suggestion, definitely give that thing a test-run.
Personally, I use a lot of guess and check in my math solving and the calculator really helps me to do that. For instance, if a question asks which fraction is the smallest, I can usually eliminate two of the answer choices right away and then I just plug the last three in the calculator to get the decimal.
I found the calculator to be a big help, I would estimate that I used it on about 15 questions.