I have lost count of the number of times that I have seen a fractional answer such as 6/4 given at the end of a student's solution, reached for my red pen, ringed the offending ink, and written, "=3/2  simplify!!!" or some other expression of frustration. Furthemore, I'm sure that I'm often guilty of writing "Always cancel your fractions." at the top of the page.If you hav