Find the value of each expression.
9p3
10c4

NPr = n! / (n - r)! 

number of permutations of 9, taken 3 at a time

9P3 = 9! / (9 -3)!
9P3 = 9! / 6!
9P3 = 9 x 8 x 7 
9P3 = 504 

nCr = n! / r! (n - r)! 

the number of combinations of 10, taken 4 at a time.

10C4 = 10! / 4! (10 - 4)! 
10C4 = 10! / 4! 6! 
10C4 =10 x 9 x 8 x 7 / 4 x 3 x 2 x 1
10C4 = 5040 / 24
10C4 = 210