Ive always felt a little left out of the traditional nerd stereotypes.
But in the spirit ofAnalog Week, Im trying to learn.
A slide rule is a multi-purpose calculator tool.
Its what people used to do math in the days before calculators and now ever-present phones and computers.
It looks like a ruler, but has a slide-y part in the middle.
You dont have to track down vintage slide rules to play along: theres avirtual slide rule right here.
See those letters next to each scale of numbers?
How to multiply
Lets say you want to multiply two numbers, perhaps 32*45.
Look at your slide rule.
The C scale is on the slide, and the D scale is on the body.
Now look at the numbers on each scale.
There are…a lot of numbers.
All of those numbers in between actually represent 1.1, 1.2, 1.3, and so on.
Lets try 32 45.
Photos of each step are in the slideshow above.
(In other words, now youre working with 3.2 instead of 32.
Youre smart, youll remember to fix the decimals in your final answer.)
So well use the index at the end.
Move the hairline to this number.
The matching number on the D scale (on the body) is the answer.
Its 1.44, but were smart about decimals, remember?
So our answer is actually: 32 45 = 1440.
Say youre trying to do 16 3.
Find 16 on the D (body) scale.
Slide the rule so that 16 on the D scale lines up with 3 on the C scale.
The C scales index will point to the answer on the D scale.
In this case, 5.3 and a smidge.
(A modern day calculator tells me the answer is 5.33333 repeating.)
