2/5 a b To get the number of factors, simply take each item from the expression and isolate it. Given the formatting limitations, I can't write the factor 2 over 5 and will instead represent it as 2/5. So the expression is 2/5ab where there's an implied multiplication between all the factors. Making that multiplication explicit, the equation becomes 2/5 * a * b And each possible factor also becomes quite explicit. Namely, the factors are 2/5 a b The reason that the 2 and 5 aren't considered factors is because technically, you could consider the 2 to be a factor, there isn't a corresponding factor of 1/5. So you have to consider 2/5 to be a single entity.