What is the value of 10c3?
a.
30
b.
120
c.
720
d.
1000

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

The answer to your question is 1/9