Copyright © University of Cambridge. All rights reserved.

Which of the following numbers is the product of exactly $3$ distinct prime numbers?

$45$; $60$; $91$; $105$; $330$

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.

*This problem is taken from the UKMT Mathematical Challenges.**View the archive of all weekly problems grouped by curriculum topic*

View the current weekly problem