The question I have been given is essencially this: Give a brief description, with some explanation, of which rational numbers between 0 and 1 have finite decimal expansions? [An example is 3/40 = 0.075, however 2/3 = 0.66666666666............] I am truly Please help. I have looked on http://mathworld.wolfram.com/DecimalExpansion.html but I need more??? anyone???