Mechanical Calculator

This very easy mechanical calculator helps elementary students to understand better the way of addition and subtraction in decimal system. The calculator is limited on three digest.

I was positively surprised, when I see that my daughters use the calculator for a lot of mathematical experiments and discuss their findings.

A demonstration you can find here: https://youtu.be/vinljlGeGMQ

For adding 496+153 first you have to do the following steps:

Turn the gear with the numbers to 000 (start with the right gear)
Turn the gears clockwise to the number 496
Turn clockwise the right gear 3 steps further, then the gear in the middle 5 steps and finally the left gear one step
The decimal carries will be done automatically. Now the gears show the result 649


For subtraction turn the gears in step 3 counterclockwise.

If you are not interested in educations, the mechanical calculator is a cool Steampunk device.