Safecracker shop 40 Math Puzzles

Product Name: Safecracker shop 40 Math Puzzles
A fantastic and unique puzzle based on a 1911 design. The goal is to have each of the 16 columns of numbers add up to 40 at the same time. Can you find a combination? There is a base ring, then 4 rings that rotate on top. To complicate things further, the rings at the top are all notched, so when the ring is turned, they expose or hide some of the numbers on the ring below. There are many possible combinations! It essentially turns 16 columns into 24 possible columns. This is quite a challenge. Size: 4.4" in diameter, about shop 0.75" in height.