We’ve been having a ton of fun for the last few weeks working through some of Catriona Shearer’s amazing puzzles. Last week I saw her share an puzzle from 2018 when she was asked for some of her favorites. Here’s that puzzle:

I thought this would be a great one for my younger son to try, and he was able to solve it.

His solution is a bit computational, so we broke his explanation into two pieces. Here he explains his approach to the problem:

With his approach drawn out now, we moved on to the computations:

Now we took a look at the twitter thread from the original problem to look for a solution that son liked. He chose the solution from Sanjay Singh

This solution was similar to how my son solved the problem, but that gave him a nice opportunity to understand the problem a bit better. Here’s his explanation of Singh’s solution:

I’m really happy that Catriona shared this problem again – it is terrific. It was also great to be reminded how long she’s been sharing these puzzles – it is going to be a long time until we get through all of them 🙂