Tally Counter Puzzle

This CAD model was designed by Oskar van Deventer, copyright (c), 5 August 2026

Tally Counter Puzzle is the serendipitous discovery that commercial tally counters happen to make an interesting puzzle. Tally counters are typically used to count people when entering a room, bus or ship. For each person, one clicks the +1 button, and the number goes up by one. The black gear at the side is turned to reset the counter back to 0000. The discovery is that one can manipulate the number cleverly by combining the +1 button and the reset knob. The puzzle is to get the counter to 9876 using as few +1 clicks as possible. The default solution is to reset to 0000 and then make 9876 +1 clicks. Smarter is to reset to 8888, and make only 988 +1 clicks. The best solution found so far is 18 +1 clicks. Is that the optimum?

Here are some links about this design.
https://www.youtube.com/watch?v=AT9wAQSV5_4

Feel free to 3D-print an extra sample to give to a friend, as long as you mention the designer and don't charge money.

If you are planning to sell some samples, then please contact me for a license agreement. The royalty fee is 10% of your selling price.

Please do not upload the design to a commercial service, or redistribute the design in any way other than linking to the YouTube video: https://www.youtube.com/watch?v=AT9wAQSV5_4

Enjoy!

Oskar
22 August 2026

Contact: 
https://oskarvandeventer.nl/index_contact.php?subject=Print%20It%20Yourself


