During my very first attempt 2 years ago, I also thought calculator was allowed until 1 day prior to the test... I was really underprepared given that I did my practice with a calculator. The thing is even with a calculator, you will not be able to calculate questions like
what is the units digit of 53^691? I would suggest you to buy a copy of the Official Guide for the GMAT, Princeton Review CAT and Kaplan800. Take the test seriously and practice problems from this forum, it will help you with the basics