Copyright © University of Cambridge. All rights reserved.

Dan has nine £$2$ coins and his sister Ann has eight £$5$ coins. What is the smallest number of coins that must change hands so that Dan and Ann end up with equal amounts of money?

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*