How to calculate combination value?

According to the formula for the calculations of the combination, it requires number of items in the set(n) and number of items selected from the set(r).

Suppose that the user enter following values:

number of items in the set (n) = 8

number of items selected from the set (r) = 3

Formula:

$$C(n,r)\;=\;\frac{n!}{r!(n-r)!}$$

$$C(8,3)\;=\;\frac{8!}{3!(8-3)!}$$

$$C(8,3)\;=\;\frac{8!}{3!5!}$$

$$C(8,3)\;=\;\frac{8!}{3!5!}$$

$$C(8,3)\;=\;\frac{8.7.6.5.4.3.2.1}{3.2.1.5.4.3.2.1}$$

$$C(8,3)\;=\;\frac{8.7.6}{3.2.1}$$

$$C(8,3)\;=\;\frac{336}{6}$$

$$C(8,3)\;=\;36$$