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**Jotaro** There’s one kind of problems dealing with permutations. I know the solving method of these kind of problems but I don’t get why does it work.

Here’s an example:

Let’s say we are given a word SCIENCE and we want find in how many ways can we rearrange letters of the word (how many permutations are there).

So, there’re 7 letters in the word. If each letter was unique number of permutations would be 7! But there’s 2 C and 2 E. So we need to divide 7! by number of permutations which these letters will make. We exclude repeated permutations (e.g. swapping places of first C and second doesn’t change anything).

So the formula will look like: 7!/(2! * 2!)

I don’t understand why do we divide. It doesn’t make any sense for me. I understand that we need to exclude repeating permutations but why does dividing work? I can’t grasp an intuition behind it