Mechanical Calculator

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This very easy mechanical calculator makes elementary students grasp addition and subtraction in the decimal system with ease. The calculator is confined to three dials. I was pleasantly surprised when I saw my daughters using the calculator for numerous mathematical experiments and discussing their findings. A demonstration can be found here: https://youtu.be/vinljlGeGMQ To add 496 and 153, follow these steps: First, turn the right dial to 000 (starting from the right). Next, rotate all three dials clockwise to 496. Then, rotate the right dial three more times, the middle dial five times, and the left dial once. The calculator will automatically calculate the decimal carry. The result is displayed on the gears as 649. To subtract, turn the dials counterclockwise in step three. If you're not interested in education, this mechanical calculator is a fantastic Steampunk device.