GMATprep1 --Function Problem

[ssraf]

for every positive integer n, the function h(n) is defined to be the product of all even integers from 2 to n, inclusive. If p is the smallest prime factor of h(100)+1 then p is between?

2-10
10-20
20-30
30-40
40+

[babachal]

here you have to begin solving the problem from 2*2+1=5, prime number is 5,
2*4+1=9 prime numbers is 3
2*100+1=201 prime number is 3 here, so answer is 2-10

[Ian Stewart]

The answer is E; the smallest prime divisor must, in fact, be larger than 50. This question has been answered many times on this forum, and you can find a few good solutions with a search. There is, for example, an excellent solution from Stuart Kovinsky here:

www.beatthegmat.com/gmat-prep-number-pr ... t8649.html

and I posted a solution here:

www.beatthegmat.com/gmatprep-function-h-n-t11711.html

There are other good solutions in other threads.

[ssraf]

thanks Ian!