In tackling this problem, I was able to determine that 1 and 3 must be among the four weights, while the other two weights fall between 10 and 30. However, because I was using an elimination-by-exhaustion approach, I didn’t explore all the possible combinations. For a one-pan scale, the five weights would be 1, 2, 3, 6, and 21.
This puzzle can serve as an introduction to combinatorics, demonstrating how different combinations can be assembled to achieve a desired outcome. Students can explore how many possible combinations exist, which work, and which don't. This encourages them to practice elimination and grouping methods, while strengthening their understanding of numerical expressions and the concept of equality.
The puzzle also ties into number theory, illustrating how numbers can be manipulated in various ways. I started to imagine possibilities beyond one- or two-pan scales. Could there be three, four, or even more pans for measuring a larger number of weights? I believe there could be a pattern that forms an arithmetic series.
