Browse · MATH
Printjmc
number theory senior
Problem
What is the smallest integer , greater than , such that is defined?
Solution
For to have an inverse , it is necessary for to be relatively prime to . Conversely, if is relatively prime to , then has an inverse .
The prime factors of include , , , and , so any multiple of any of these primes does not have an inverse . This rules out all the integers from to . However, is relatively prime to , so is the smallest integer greater than that has an inverse .
The prime factors of include , , , and , so any multiple of any of these primes does not have an inverse . This rules out all the integers from to . However, is relatively prime to , so is the smallest integer greater than that has an inverse .
Final answer
11