[Math] factorial division when the bottom number is larger than the top number

Question

I have a factorials problem to solve, and I do not know the method of solving it.

I know how to do one number factorials (e.g. 5!, 15! etc…) and factorial division where the top number is larger than the bottom number.

Could someone please make a simple guide (with an example question/answer please) on how to solve a factorial divison such as:

100!/102!

I've tried so many searches on google no one has expained this type of question

Thank you very much.

Answer 1

Hint:

$$\dfrac{100!}{(102)!} = \dfrac{100!}{102\cdot 101\cdot 100!}$$

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