Doing some "how many combinations" calculation 1. The problem statement, all variables and given/known data We're given the number 123215. How many different numbers can we get by changing the order of the digits? This is a six-digit number, so there are six positions for each digit. This is an unsorted selection with covering (not sure if that's what you call it in English). 3. The attempt at a solution I've tried nCr, nPr and pretty much everything that's tryable;) I just can't get it right. I know for a fact that the correct answer is 180.