http://www.amazon.com/s/ref=nb_ss_gw/104-3390316-7358362?initialSearch=1&url=search-alias%3Daps&field-keywords=GED

Most of them should have practice problems in them. Also if they could with a cd rom, they most likely even have more practice problems.

Also you can google “ged practice tests” and try the math and science questions there. And if you come across a math problem you do not know how to work, you could ask the people on here or google it to learn how. (the ged books, would probably help you work out most kinds of problems.)

Good luck!

http://www.associatedcontent.com/article/34260/you_can_do_it_successfully_passing.html

http://www.doe.mass.edu/ged/geninfo.html

http://www.ncsall.net/?id=403