How Many of You Have Used a Slide Rule?

Ahh… Glad to hear from you, don’t recall many of my contemporaries using Pickett, most had K&E, Post, etc.

I’m a fan of the DF/CF scales, too, several things they come in handy for. Nice thing about both of them is that the fold point is precisely Pi. If you need the circumference of a circle, set the diameter (say, 2.00) on the D scale and read the circumference (6.28) directly off the DF scale, without moving the slide.

Another slide rule method I still use today is the order of calculation. Say, you need (37 x 4.70) / (3.21 ^ 2). On a calculator, I enter that as 37 x 4.70 / 3.21 / 3.21
Using a slide rule you would have to write down the value 3.21 ^ 2 if not solved in a chain calculation.

Thanks, glad you found that link.

Brings back a lot of memories. Also started college without knowing how to use one. They had orientation classes at nights to teach us how they worked.

Bought both a Post and a Pickett Pocket to carry to class. Used for 4 years of BS and 1 year of grad school.

Our student chapter of ASCE bought a $495 scientific calculator in 1972 which we raffled off at a hockey game. Made a lot of money selling $1 raffle tickets. And we all took turns trying it while selling the tickets.

Started work with slide-rule. My dad (also a Civil Engineer) got me a $150 TI calculator for Xmas 1973. It only had square-root and X^2. Still used slide-rule for trig functions.

I used a slide rule in high school but by the time I got to college calculators and computers were already being used.

It makes a good back-scratcher. So… yeah… I’ve used a slide rule.

Makes a good nutcracker too.

…and with the tap of a hammer, it makes a pretty good guillotine, too. Still have the old case for my original one… painted flat black with a red heart painted in glossy paint, and an atomic mushroom painted in the heart… that was the kinda kid I was when I first started engineering.


I still have, and can actually find, the first slide rule I ever had. A plastic Pickett model 120, and I have both the sleeve and the instruction booklet for it as well. Got it as a gift I think when I was a sophomore in high school, probably 1962. I also still have a Pickett N3-ES that I used during college and into my first job upon graduation - somewhere along the way it has managed to lose one of the screws holding the piece with the K, A and extended SQRT scales in place. There’s also a 6" Pickett somewhere in the house. Sadly, I’m more than a bit rusty as far as using them is concerned. Needing +3 reading glasses to use them at all isn’t helping.


I grew up in the “graphing calculator that can do calculus for you” era. Not being able to afford that model, I had to settle for a regular graphing calculator :rofl:

Saw my first slide rule in college, when a professor said they keep it in their office as a momento from their dad, an engineer that routinely did calculations at the kitchen table with the thing.

How do you administer CPR to a slide rule?

Don’t you just hate it when the batteries run out… and the sliderule dims and turns off… just got my new calculator, a week back… a TI Nspire CXII CAS… does just about everything but talk to me…


@dik…say it ain’t so…no RPN?
@MSQUARED48…carefully…those sharp corners are hell.

@Ron RPN… that’s the reason the HP calculators were so popular… they were fast. They used the ‘stack architecture’ of the processor, just like the Forth programming language designed by Chuck Moore. This allowed observatories to ‘work’ in ‘real’ time for controls.

I’m tutoring a Grade 12 student in Pre-Calculus and the TI is great… I used to like HP, but, their quality started going downhill about 20 years back. I used to have a desktop HP that used a tape drive… and still use my HP 48GX occasionally… but the TI beats it thumbs down… there is no comparison, including the 80MB of RAM.

Should have added that I used to program in Forth before HP came out… 50 years back… there was nothing close to it for speed… way back when processors were slow…


After working with RPN for over 40 years, I find any other logic very difficult.

@MSQUARED48…same here Mike

My slide rule didn’t come with RPN, so for all these years I’ve had to do without that un-other logic. It isn’t programable and has no RAM either, but I’ve never had to replace the batteries in all these years.

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I have no problem using either… after a few seconds, just like I’ve been using it for years… my preference is the algebraic logic, and I used to like the RPN due to the speed… no longer an issue.


Good thing about a slide rule…it can be either logic structure depending on how you want to chain your calculations :grinning:

And it doesn’t need batteries - well, at least mine didn’t.

I’ve had mine for 48 years…no battery change…yet

53 years for my K&E, and 55 years for my Pickett.