# Factorials!

## Statisticians use factorials when calculating potential combination and permutations and using the binomial equation. A factorial, represented by an explanation mark (!), denotes a multiplication of the sequence of descending (natural) numbers. For example, 5! equals 5*4*3*2*1. 1! = 1. And n! = n * (n-1)!

# A Practice Problem!

## Solve: **x=10!/8!**

## Solution: So we can break down 10! into 10*9* 8! . We then know that 8! in the numerator cancels out the 8! in the denominator, which leaves us 10*9 in the numerator, and therefore **x=90**.

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