Skip to main content
OlympiadHQ

Browse · MATH

Print

jmc

number theory senior

Problem

How many of the divisors of are larger than ?
Solution
Suppose that divides and that . Taking the reciprocal of both sides of and multiplying by , we find . There are 7 positive integers less than 8, and can be chosen so that takes on any of these values, since ranges over all the divisors of 8! as ranges over the divisors of . Therefore, divisors of 8! are greater than .
Final answer
7