explanation of how 0 equals 1
C(n,k) is the number of combinations you can make of k objects out of a given set of n objects. We see that C(n,0) and C(n,n) should be equal to 1, but they require that 0! be used. So 0! = 1 neatly fits what we expect C(n,0) and C(n,n) to be.(n,k) is the number of combinations you can make of k objects out of a given set of n objects. We see that C(n,0) and C(n,n) should be equal to 1, but they require that 0! be used. So 0! = 1 neatly fits what we expect C(n,0) and C(n,n) to be.