exam Maths Puzzle Numerical Ability

The problem is P(n,2)=42, find n. The instructor gave the answer for n, which is 7. I figured out the formula knowing the answer is 7, which is n!/(n-k)!
I need to know the formula to figure out how to get the value of n. Thank you.

Read Solution (Total 0)

exam Other Question

Thank you for your help.Solving the following by Factoring the equations of x^2-6x-16=0, would (x+2)(x-8)=0 or -8x+2x, and would the same apply to 6x^2+42x=0,6x(x+7). Is x2 the same as x^2. This site has truly been a big help for me. The Nys had eight grandchildren in 2002. In 2003, they had 12 grandchildren. Find the percent increase in the number of grandchildren from 2002 to 2003.