[megatherium]

Here is a rather easier technique for adding two simple fractions: Remember the formula a/b + c/d = (ad+bc)/(bd). The trick is that you remember the formula by writing a/b + c/d in the usual vertical format and drawing a cross over the two fractions (so that the cross joins the a and d, and also the b and c -- that produces the numerator ad+bc). This works best for small fractions, in that the denominator bd may not be as small as the least common multiple of b and d. But it requires little work or thought to perform: just remember the cross pattern for the numerator, and multiply the denominators.

[patton]

It works, but if you don't reduce it, you only get 1/2 credit.