ITOM 2016 Phase I Note 1

| Order matters | Order does not matter--------------------------------------------------------------------------------------------------------------------------------------------------Repetition allowed | n^r | nHr = n+r-1Cr--------------------------------------------------------------------------------------------------------------------------------------------------Repetition not allowed | n(n-1)(n-2)...(n-r+1)=n!/(n-r)!=nPr | n(n-1)(n-2)...(n-r+1)/2=n!/r!(n-r)!=nCr