Another thing to add: you're not allowed to erase anything! I had gotten into the habit during practice where I erased bad attempts or wrong numbers so that I wouldn't confuse myself. However, I was told at the testing center that you're not allowed to erase anything on the sheets.
And I agree with everyone who said that there are plenty of pages. The book that I had at my testing center consisted of 6 sheets of laminated, legal-size, yellow graph paper. I used it to jot down ideas for the AWA essays and then for the quant. section. I barely used 3 sheets (double-sided).
I must say that I was very relieved about the sheets and the quality of the pen (fine-point) since I had heard horror stories about people receiving what were basically dry erase boards of the kind that we used to hang on our dorm room doors and fat dry erase markers that were half dried up.