Story Prime

What is the last prime he needs to check before he can conclude that 457 is prime?

To determine whether 457 is a prime number, Damien investigates by testing the divisibility of smaller prime numbers. If he starts by checking the primes 2, 3, 5, 7,...., what is the last prime he needs to check before he can conclude that 457 is prime?

Public Comments

1. (457)^1/2=21.3775 2,3,5,7,11,13,17,19is the last pn he must check.