This Instructable will show you how to make a functioning lego calculator that can add +,subtract -,multiply x, and divide \! It uses a gear train that turns one rotation of the control knob into a tenth of a rotation on the tens dial. By engaging, rotating to numbers, and disengaging the control knob in patterns you can do basic arithmetic. Thank you and enjoy!!
Step 1: Make Base And Frame
You can place the two supports anywhere on the base as long as you keep the supports two studs apart. It depends on how tall your paper indicator is.