You'll know the answer when you learn what combinations are all about.
C(N,R) is read "Suppose you have N things and you want to choose R from them.
C(N,R) equals the total number of ways there are to do that."
Example:
C(4,3) is read "Suppose you have 4 things and you want to choose 3 from them.
C(4,3) equals the number of ways there are to do that. So C(4,3)=4, That's
because if you have this set of four {a,b,c,d} You can choose these 4 ways:
{a,b,c}, {a,b,d}, {a,c,d}, {b,c,d}. Leave a different one out from the 4 each
time.
C(6,0) is read "you have 6 things and you want to choose 0. How many ways are
there to do that."
So
C(6,0) is read as: "Suppose you have 6 things and you want to choose 0 from
them. C(6,0) equals the number of ways there are to do that." The answer is
obviously 'exactly 1 way', simply "choose none" which just means not to choose
any! It's really a trick question because it is very obvious, yet very tricky
to see that it is obvious.
Answer: 1 way, just don't choose any! So C(6,0) = 1.
[Similarly, C(6,6) also equals 1 because there is just one way to take all 6 --
simply 'take all six'!. You may run into that sort of problem later.]
Edwin
