One of my personal favorite math puzzles is the Safecracker 40. The brain teaser is based on a 1911 design and available once again in laser engraved alder wood. This is an ideal intermediate level of difficulty puzzle recommended for ages 12 and up.
The idea of the puzzle is simple, just line up each of the 16 columns so that when added together each one equals 40. Sounds easy right? Well, not so fast! There are over 7,000 different possible configurations with only one providing the correct solution. This is not just a brute force style of puzzle, however. You will be able to logically work towards the solution by identifying the relationship of the numbers on each ring. Check out the video below for e full breakdown on how the Safecracker works by Creative Crafthouse Owner and Founder Dave Janelle.