I've owned a bright yellow Pickett slide rule since about 1964 or 1965; I bought it with money I had saved while delivering newspapers before school every day.

I've owned a bright yellow Pickett slide rule since about 1964 or 1965; I bought it with money I had saved while delivering newspapers before school every day. It was my second "computer" -- my first was a Chinese abacus. I was never practiced enough to be good at an abacus, but learning to use a slide rule is pretty easy. First, learn how logarithms can be used to do computation. Back then every engineer or even science student, as I was, learned to use tables of logarithms to perform multiplication, division, and exponentiation rapidly. Today this is a bit of a lost art, but if you understand it, the operation of a slide rule becomes obvious. The most basic scales are just marked off logarithmically. The scales are a compact version of the log table values. Appending logarithmic scales corresponds to multiplication and so forth. It's like learning vim, learn a few basics and then tinker around with it to get better. The great multiplicity of scales on slide rules from that period also provided access to trig values, natural logs, hyperbolics, square roots (same log scales but scaled by half), etc. For many problems, one could approach three significant digits of accuracy with a slide rule. The scales didn't have to be straight they could be circular. This led to a circular slide rule, less convenient to hang from ones belt in a holster, but with some larger (and some smaller) resolution scales. I have even seen cylindrical slide rules with helical scales wrapped around the surface of a cylinder. These could obtain an extra digit or more of accuracy.