**A person uses nPr when the order matters, and they use nCr when order does not matter or for combinations.** Someone would use these functions when performing probability math problems.

Probability math looks at the likelihood of something happening. Not all events have a predictable outcome, so someone uses probability to essentially predict the outcome. For example, if someone flips a coin, when the coin lands it will either be on the tails side or the heads side. Since there are only two sides of a coin, there is a 50 percent probability that the coin lands on heads, or a 50 percent probability that it lands on tails.