They come in the form of fractions because the numerator and denominator contain factorials. To simplify such type of problem, expand the factorials on top and at the bottom, cancel out common factors, and finish off by simplifying the leftover numbers.

How do you get rid of factorials?

Compare the factorials in the numerator and denominator. Expand the larger factorial such that it includes the smaller ones in the sequence. Cancel out the common factors between the numerator and denominator. Simplify further by multiplying or dividing the leftover expressions.

What is the rule for factorial?

So the rule is: n! = n × (n−1)!