Question

What is the value of 10C3?

A.
30

B.
120

C.
720

D.
1000

Answer 1

The answer is B. 120

nCr = n! / ((r! * (n - r)!)

n = 10
r = 3

10C3 = 10! / ((3! * (10 - 3)!)
= 10! / ((3! * 7!)
= (10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1) / (3 * 2 * 1 * 7 * 6 * 5 * 4 * 3 * 2 * 1)
= 3628800 / 30240
= 120