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.