I have a strange confession? This morning when I woke up, before getting out of bed, I reached for a piece of technology on my bedside table, and it wasn’t my phone. It was my mom’s old slide rule (pictured below). Recently I became obsessed w/ these analog calculators. So here’s a 🧵 on how to make one (so you can see how they work). First, two things make slide rules possible: (1) you can add by stacking rulers; & (2) you can multiply by adding logs, that’s because log(x) + log(y) = log(x*y)