Baa Baa Black Sheep, Have You Any Blogs?


Story: Okay, so it’s been like four days since I’ve gone walking, which is four days too many, so I decided to walk down to Chinook Centre (about 13 miles round trip). However, once I got down there, I changed my mind and decided to check out the Value Village close to the mall instead. I was just going to look around since I have practically no money at the moment, but when I was digging through the miscellaneous baskets on one of the shelves I came upon THIS:


And since it was only $2, I had to get it. So I did.

It didn’t have a manual or anything with it and I’ve never used a slide rule before in my life, so I went to teh internetz to see if I could figure out how it works. And it’s super cool! Let me show you a few basic things.

Multiplication: Say I wanted to multiply 1.2 by 3. What I’d do is find 1.2 on the “D” scale and slide my “C” scale so that its 1 is right above 1.2.


Then I would find 3 on my “C” scale. Whatever number on the “D” scale is right below the 3 on the “C” scale is the product of 1.2 times 3: 3.6!


Division: Let’s do 6 divided by 4. You take the divisor, 4, on the “C” scale and set it above the dividend, 6, on the “D” scale like so:


The quotient is whatever number is on the “D” scale right below the 1 on the “C” scale: 1.5!


Finding a square root: Say I wanted to find the square root of 5. I would find  5 on the “A” scale. Whatever number on the “D” scale that is below that 5 is the square root: approximately 2.23!


Super cool. You can also do things like cubes/cube roots, proportions, logarithms, and sines and tangents of angles, but I’m still learning.



2 responses

  1. Slide rules are really cool, but very cumbersome to use. Kind of amazing to think that all science and engineering was done with a slide rule. The dudes that designed the golden gate bridge used freaking slide rules. My favorite was the Canadian Pacific spiral tunnels, designed and built with nothing but slide rules, and they were only 1/4″ off when they met in the middle. Crazy! Makes one really appreciate an electronic calculator.


    1. Haha, I think I read about that somewhere. It really does make you appreciate the electronic ones.


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