Question 475581
nPr/nCr=r! --> r!= 3024/126= 24 --> r=4 ....--> r!=24=4*3*2*1=4!

nC4= 126 --> n·(n-1)·(n-2)·(n-3)/24= 126 --> n·(n-1)·(n-2)·(n-3)= 3024
--> n=9 it is a solution