If I can't remember the exact amount i spent on books for college do I just estimate?

[AnnetteB]

You can estimate the cost of your books, but be aware that if your return was examined by the IRS for some reason, you may be asked to provide proof (receipts) to back up the numbers that you enter. 

If you cannot find your receipts and you must estimate, it is better to under-estimate than over-estimate.