Question

complete the series 10,45,120,210,?

Answer 1

Start with 10 Multiply 10 by 9, get 90, divide by 2, get 45. Multiply 45 by 8, get 360, divide by 3, get 120. Multiply 120 by 7, get 840, divide by 4, get 210. Multiply 210 by 6, get 1260, divide by 5, get 252. <--- answer Answer: 252 Or you can do it this way with combinations of 10 things taken 1,2,3,4,5 at a time. C(10,1) = 10 C(10,2) = 45 C(10,3) = 120 C(10,4) = 210 C(10,5) = 252 <--answer