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What would be the value of n, when nP3=210? - Quora

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What would be the value of n, when nP3=210? - Quora

Why is n^k/k! not the correct number of ways to select k objects from n objects with replacement (order not important)? - Quora

I had a question on a test, where I was supposed to subtract combinations in forms n choose k (binomial coefficients), the answers were also in forms n choose k, is there

How to solve the differential equation derivative of a function f equals to inverse of the function f - Quora