How many distinct permutations are there of the word statistics?

We know there are 10! (ten factorial) permutations (that's about 3,628,800 permutations); however, we know that number includes repeated permutations, as there are 3 s', 3 t's and 2 i's. So we have to divide by the number of ways these can be written as individual permutations (if they were considered as unique elements), which are 3! (= 6), 3! and 2! (= 2) respectively.

So our final calculation would be 3628800 / (6 * 6 * 2) = 50400 unique permutations.