P(n,n-1)=6
P(n,n-1) = 6
P(n,r) = n! / (n-r)!
P(n,n-1) = n! / (n-(n-1))!
6 = n! / (n-(n-1))!
6 = n! / (n-n+1)!
6 = n! / (1)!
6 = n! / 1
6 = n!
We knew that 3! = 6 , so n = 3
#kyuri
