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.
<p>Hola Amigos!</p>
Its awesome ,i messed up :( i fixed it though
<p>nice..could anyone tell me where should i get(buy) all the lego parts??</p><p>thank</p>
<p>I liked it, for real, but I see you made a mistake. </p><p>dividing is NOT subtracting the same number over and over again.</p>
<p>Actually it is, You count how many times you can subtract a from b.</p><p>http://www.homeschoolmath.net/teaching/md/division-repeated-subtraction.php</p>
<p>mm, I just thought he meant the actual result of some substraction was the division... which made no sense. </p>
<p>For sure his explanation is not complete for both multiplication and division. </p>
<p>dividing is counting how may times it takes to subtract a dividend by the divisor, so yeah it is subtracting by the same number over and over again, why do you think in long division you subtract and come to the same answer that a calculator would</p>
Thanks, Qtechknow!<br>
<p>Nice job!!!</p>
<p>I'm going to round up the kiddos and try this right now!</p>
<p>Ha! Brilliant!</p>
<p>Excellent work!! Curt Herzstark would have been proud. Check out this video of how his Curta calculator works. https://www.youtube.com/watch?v=loI1Kwed8Pk</p>
<p>Ingenious! Babbage would be proud. I teach a course in Digital Logic Design from time to time and in the introductory lecture I touch on the history of computation, which features an adding machine. I plan to build one of these and use it as a demonstrator--great job!</p>
<p>what a great idea, great job</p>
Awesome ! I had a little mechanical calculator but it could just multiply !
<p>This is amazing, I've never seen anything like this before!</p>

About This Instructable




Bio: Engineer, author, 3DP lover and proud airsoft wielder.
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