Arithma Addiator and Instamatic by FEDTRO, Troncet-Style Mechanical Calculators

The Addiator and Instamatic are perhaps the simplest mechanical calculators you can imagine, but they're quite clever. I walk through how to add, subtract, and multiply, and talk a bit about these interesting vintage adding machines. They're from the 1950s or 1960s, but their design goes back to the late 1900s at least (and possibly further than that) to a patent by Louis Troncet. 00:00 – Intro 00:22 – Overview and carry mechanism 01:25 – Compared to slide rules and multiplication 02:51 – Subtraction using nine's complement 03:26 – Outro Watch all my "Counting in 2021" videos about mechanical calculators here:    • Плейлист