Visit the following websites with your math questions:

http://www.themathpage.com/aPreCalc/rational-irrational-numbers.htm#rational1

http://www.math.com/

http://www.aplusmath.com/

http://mathforum.org/dr.math/

http://www.cut-the-knot.org/do_you_know/numbers.shtml#rational

http://www.glencoe.com/sec/math/algebra/algebra1/algebra1_05/