SOLUTION: Can someone please go in depth and explain to me how to do 21 C 19 and 16 C 3 i don't wanna use the calculator

Algebra ->  Permutations -> SOLUTION: Can someone please go in depth and explain to me how to do 21 C 19 and 16 C 3 i don't wanna use the calculator       Log On


   

Question 732691: Can someone please go in depth and explain to me how to do 21 C 19 and 16 C 3 i don't wanna use the calculator
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

21C19=21%21%2F%28%2821-19%29%21%2A19%21%29



21C19=%2821%2A20%29%2F2
21C19=21%2A10
21C19=210


do second one using same formula:

16C3=16%21%2F%28%2816-3%29%21%2A3%21%29






16C3=%2816%2A15%2A14%29%2F%283%2A2%2A1%29
16C3=%28cross%2816%298%2Across%2815%295%2A14%29%2F%28cross%283%29%2Across%282%29%2A1%29
16C3=8%2A5%2A14
16C3=560