Maths question

Question

2. Factorial zero is

(a)injure

(b)assist

(c)heal

(d)embellish

Answer 1

1! = 1

0! = 1, which may come as a surprise

2! = 2x1 = 2

3! = 3x2x1 = 6

n! = nx(n-1)x (n-2) x ... 3 x 2 x 1

0! = 1. You can see that from the combination formula

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

then nCr = n!/n!0! = 1 regardless of what n equals