Anyone still using a slide rule for calculations instead of calculators or computers?

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#1 21662980 14 Jul 2012 19:52

Floy Viola Floy Viola

Anonymous

Post #1
21662980 14 Jul 2012 19:52

Do any of you guys still use a "slide rule" for their calculations? its just a trivial questions
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#2 21662981 14 Jul 2012 22:31

Ashesh Sharma Ashesh Sharma

Anonymous

Post #2
21662981 14 Jul 2012 22:31

http://www.hpmuseum.org/srinst.htm
go to this link
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#3 21662982 14 Jul 2012 23:01

Floy Viola Floy Viola

Anonymous

Post #3
21662982 14 Jul 2012 23:01

thanks for the link, but my question is "do any of you guys use a slide rule?", bcoz i still do. it's very easy to calculate resistor ratios as a voltage divider.
#4 21662983 15 Jul 2012 00:14

Steve Lawson Steve Lawson

Anonymous

Post #4
21662983 15 Jul 2012 00:14

Haven't used a slide rule since high school back in '73. Had a Chemistry teacher that hadn't caught the wind of change, and insisted on drilling us on the slide rule the whole semester. In fact, if he even saw a calculator it was an instant F!

I guess I'm still rebelling
#5 21662984 15 Jul 2012 04:35

Elba R Dalet Elba R Dalet

Anonymous

Post #5
21662984 15 Jul 2012 04:35

Not really, but I have some of them.
In the past I used them a lot,

Regards
#6 21662985 15 Jul 2012 15:11

Joe Wolin Joe Wolin

Anonymous

Post #6
21662985 15 Jul 2012 15:11

Floy,

I don't even know how to use a slide rule!

But this conversation peaked my interest enough to find this online version and try to figure it out...

http://www.antiquark.com/sliderule/sim/n909es/virtual-n909-es.html

During a nuclear holocost or EMP attack, these things will be worth their weight in gold.
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#7 21662986 16 Jul 2012 06:53

Peter Evenhuis Peter Evenhuis

Anonymous

Post #7
21662986 16 Jul 2012 06:53

i have one on my smart phone ????????????
#8 21662987 16 Jul 2012 19:31

Floy Viola Floy Viola

Anonymous

Post #8
21662987 16 Jul 2012 19:31

hi steve,

it's heartwarming to know that there are still guys using the slide rule.
#9 21662988 17 Jul 2012 05:40

David Adams David Adams

Anonymous

Post #9
21662988 17 Jul 2012 05:40

I can use one but being in engineering for so long - I don't even use a calculator that often. Most of the time I can round off the numbers and do calculations in my head, I can usually get within 10 percent of the answer that a calculator gets but still need the calculator for log functions. . Never did learn to use the slide rule for that. When I was in the Navy Nuclear power prgram they spent 2 weeks (8 hours a day) teaching you how to use the calculator.

The use of calculators in today's society has ruined man's ability to manipulate numbers. For proof of that statment - just ask any high school graduate to calculate the square root of a number without the use of a calculator, or use tables to determine the value of sine(37.5) degrees.

Or how about asking an Engineering student to make a bode plot without the use of EXCEL. Which means making a graph manually. Semi-log paper - remember that ??
#10 21662989 17 Jul 2012 10:35

Richard Comerford Richard Comerford

Anonymous

Post #10
21662989 17 Jul 2012 10:35

I still have the slide rule I used in college in a glass-covered shadow box over my computer at work. It has a label on it that says, "In Case of Emergency, Break Glass."

Around my junior year, TI calculators became available and every engineer had to have one; we never looked back. We used to carry our slide rules around , and later our calculators, attached to our belts like some people do today with smart phones.

I've used mine in recent memory for fast decimal multiplication at times when I only need three-digit accuracy, which isn't very often.

BTW, Does anyone remember how to use all the different scales on a slide rule? Mine has 25.
#11 21662990 17 Jul 2012 10:42

David Adams David Adams

Anonymous

Post #11
21662990 17 Jul 2012 10:42

I love the "in Case of Emergency-break glass". As for the 25 different scales - better get a computer to find out. I still like the look up tables better than the slide rule. As for the invention of hand held calculator. It wasn't till my second year undergrad that I had a calculator that had built-in sin, cos and log function. and it cost close to $100 back then. Did I just date myself - Hmmmmmm
#12 21662991 17 Jul 2012 10:53

Richard Comerford Richard Comerford

Anonymous

Post #12
21662991 17 Jul 2012 10:53

Mr. Sharma's link ("slide rule scales":http://www.hpmuseum.org/srinst.htm) mostly answers my question. But my Ricoh slide rule also has a P scale that runs logarithmically from 0 to .995. Don't remember what that was for.
#13 21662992 17 Jul 2012 10:55

Richard Comerford Richard Comerford

Anonymous

Post #13
21662992 17 Jul 2012 10:55

Talk about dating yourself, I remember using a book of log tables to solve trig problems.
#14 21662993 17 Jul 2012 11:01

Richard Comerford Richard Comerford

Anonymous

Post #14
21662993 17 Jul 2012 11:01

Me too, Peter. It's the one from TestTubeGames.com. I also have their sundial, which is fun too.
#15 21662994 17 Jul 2012 19:57

Floy Viola Floy Viola

Anonymous

Post #15
21662994 17 Jul 2012 19:57

hi adam,

i like what you said "The use of calculators in today’s society has ruined man’s ability to manipulate numbers. For proof of that statment – just ask any high school graduate to calculate the square root of a number without the use of a calculator......
#16 21662995 17 Jul 2012 20:00

Joe Wolin Joe Wolin

Anonymous

Post #16
21662995 17 Jul 2012 20:00

A little off topic, but in-case you folks haven't used it yet, we have a pretty good engineering calculator we made called "eCalc"

http://www.eeweb.com/toolbox/calculator

It works in both algebraic and RPN modes and also supports complex numbers.

Enjoy...
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#17 21662996 18 Jul 2012 07:49

David Adams David Adams

Anonymous

Post #17
21662996 18 Jul 2012 07:49

And then how many people know what RPN means. In the early days only HP used it. Dang - dated myself again.
#18 21662997 18 Jul 2012 08:25

Richard Comerford Richard Comerford

Anonymous

Post #18
21662997 18 Jul 2012 08:25

And why "Polish". From another member of the SAE (Society of Aging Engineers)
#19 21662998 18 Jul 2012 12:09

Steve Lawson Steve Lawson

Anonymous

Post #19
21662998 18 Jul 2012 12:09

It's also used in the Forth language (stack based calculation). I had a lot of fun with Forth back when.
#20 21662999 18 Jul 2012 17:45

Joe Wolin Joe Wolin

Anonymous

Post #20
21662999 18 Jul 2012 17:45

Sounds like because it goes against that of Poland ;-)

http://en.wikipedia.org/wiki/Polish_notation
#21 21663000 19 Jul 2012 09:13

Richard Comerford Richard Comerford

Anonymous

Post #21
21663000 19 Jul 2012 09:13

And why not "Hsilop notation"? I guess if had been Zciweisakul notation, no one would have known how to say it.
#22 21663001 25 Oct 2012 11:31

Gregg Williams Gregg Williams

Anonymous

Post #22
21663001 25 Oct 2012 11:31

My college professor made us use the slide rule a few time in class to give us the experience. I also have a professor that has us use it for one project in our online engineering class: https://www.purdueonlineengineering.com/electrical-engineering/ - It was interesting to use but I will stick with more modern devices
#23 21663002 25 Oct 2012 23:52

madhurika Shrivastava madhurika Shrivastava

Anonymous

Post #23
21663002 25 Oct 2012 23:52

The slide rule, also known colloquially (in the US) as a slipstick,[1] is a mechanical analog computer. The slide rule is used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry, but is not normally used for addition or subtraction.

Slide rules come in a diverse range of styles and generally appear in a linear or circular form with a standardized set of markings (scales) essential to performing mathematical computations. Slide rules manufactured for specialized fields such as aviation or finance typically feature additional scales that aid in calculations common to that field.

William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. Before the advent of the pocket calculator, it was the most commonly used calculation tool in science and engineering. The use of slide rules continued to grow through the 1950s and 1960s even as digital computing devices were being gradually introduced; but around 1974 the electronic scientific calculator made it largely obsolete[2][3][4][5] and most suppliers left the business.

dainik bhasker
#24 21663003 26 Oct 2012 09:07

Richard Comerford Richard Comerford

Anonymous

Post #24
21663003 26 Oct 2012 09:07

Can you say, "Wikipedia"?
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Topic summary

✨ The discussion centers on the continued use and relevance of slide rules for calculations in the modern era dominated by calculators and computers. Some participants still use slide rules for specific tasks such as calculating resistor ratios in voltage dividers or for quick approximations requiring limited precision. Others recall learning and using slide rules extensively in education and early engineering careers, noting the transition to handheld calculators like those from Texas Instruments. The conversation highlights the decline in manual calculation skills due to reliance on digital tools, with references to logarithmic and trigonometric functions, semi-log graph paper, and Bode plots. Virtual slide rule simulators and smartphone apps are mentioned as modern adaptations. The discussion also touches on Reverse Polish Notation (RPN) calculators, their historical association with Hewlett-Packard, and the availability of online engineering calculators supporting algebraic and RPN modes. Historical context includes the invention of the slide rule by William Oughtred based on John Napier's logarithms and its widespread use before pocket calculators. Specialized slide rules for fields like aviation and finance are noted for their additional scales. Overall, the thread reflects nostalgia, practical use cases, and educational value of slide rules alongside modern computational tools.

FAQ

TL;DR: Yes—people still use slide rules for quick, 3‑sig‑fig work. One engineer recalls “two weeks (8 hours/day) of calculator training,” and warns: “The use of calculators…has ruined man’s ability to manipulate numbers.” [Elektroda, David Adams, post #21662988]

Why it matters: If you tinker, study, or work where batteries die or devices are banned, a slide rule stays fast, durable, and EMP-proof.

Quick Facts

Typical accuracy: about three significant digits, fine for quick engineering estimates. [Elektroda, Richard Comerford, post #21662989]
Core functions: multiplication, division, roots, logs, and trig; not for addition/subtraction. [Elektroda, madhurika Shrivastava, post #21663002]
Obsolescence timeline: handheld scientific calculators displaced slide rules around 1974. [Elektroda, madhurika Shrivastava, post #21663002]
Virtual tools exist (e.g., N909-ES simulator) for practice without hardware. [Elektroda, Joe Wolin, post #21662985]
Phone apps and web calculators (eCalc; RPN support) offer modern alternatives. [Elektroda, Joe Wolin, post #21662995]

Do people still use slide rules instead of calculators or computers?

Yes, mainly for quick estimates, education, or as a no‑power backup. Several posters still own and occasionally use slide rules for fast multiplicative tasks and voltage‑divider ratios. One keeps a slide rule “In Case of Emergency, Break Glass” above his workstation, underscoring its backup role. [Elektroda, Richard Comerford, post #21662989]

How accurate is a slide rule in practice?

Expect about three significant digits. That level suits resistor ratios, scaling laws, and sanity checks. One engineer notes using a slide rule for fast decimal multiplication when only three‑digit accuracy was needed. For tighter tolerances or statistics, use a scientific calculator or software. [Elektroda, Richard Comerford, post #21662989]

What calculations are slide rules good at—and not good at?

They excel at multiplication, division, roots, logarithms, and trigonometry. They do not perform addition or subtraction directly. Treat them as an analog computer for proportional reasoning and order‑of‑magnitude checks. For sums and differences, switch to pencil‑and‑paper or a calculator. [Elektroda, madhurika Shrivastava, post #21663002]

How do I quickly compute a resistor divider with a slide rule?

Set the C scale 1.0 under the top resistor value on the D scale.
Move the cursor to the bottom resistor value on C.
Read the ratio R2/(R1+R2) or R1/R2 as needed, then apply to input voltage for Vout. “Great for resistor ratios as a voltage divider.” [Elektroda, Floy Viola, post #21662982]

Is there a free way to learn without buying a slide rule?

Yes. Use the online N909‑ES virtual slide rule to practice movements, cursor alignment, and reading scales. It mirrors classic linear rules and includes guides. Start with multiplication/division, then try logs and square roots. [Elektroda, Joe Wolin, post #21662985]

What does RPN mean, and why do engineers mention it with calculators?

RPN stands for Reverse Polish Notation, a stack‑based entry method used by classic HP calculators and favored by some engineers for speed. It also appears in the Forth language, which uses stack operations for calculations. [Elektroda, Steve Lawson, post #21662998]

Why is it called “Polish” notation?

It references logician Jan Łukasiewicz, who introduced Polish notation; RPN is the reversed form. A poster quips it’s named because it goes “against that of Poland,” linking to background on Polish notation. [Elektroda, Joe Wolin, post #21662999]

When did slide rules fall out of mainstream engineering use?

Around 1974, affordable handheld scientific calculators displaced them in classrooms and labs. By the mid‑1970s, most suppliers exited the market as engineers adopted TI and HP calculators. [Elektroda, madhurika Shrivastava, post #21663002]

Are there smartphone apps or modern tools that mimic slide rules?

Yes. Users report slide‑rule apps on smartphones and recommend web calculators like eCalc, which supports algebraic and RPN modes and complex numbers. These help practice workflows and handle advanced math when precision is required. [Elektroda, Joe Wolin, post #21662995]

How steep is the learning curve compared to a calculator?

It’s approachable. One member trained two weeks at 8 hours per day on calculators, yet still values mental math and tables. A slide rule builds number sense through estimation and scale reading. “The use of calculators…has ruined man’s ability to manipulate numbers.” [Elektroda, David Adams, post #21662988]

What’s an edge case where a slide rule beats digital tools?

During power loss, device bans, or EMP events, a slide rule still works. One commenter joked these will be “worth their weight in gold” after a nuclear or EMP event, highlighting resilience as the differentiator. [Elektroda, Joe Wolin, post #21662985]

Which brands or models do posters remember using?

Mentions include HP (RPN heritage) and TI calculators arriving during junior years, which rapidly replaced slide rules. Some keep Ricoh slide rules and display them as memorabilia, yet still use them for quick decimal math. [Elektroda, Richard Comerford, post #21662989]

What are common slide‑rule scales, and what does the P scale do?

Common scales include C/D for multiplication/division, and trig/log scales for angles and logs. Posters reference comprehensive scale guides that explain specialized scales like P, which assist with certain trigonometric relationships and powers on some models. “See the slide‑rule scales guide.” [“Slide Rule Scales – HP Museum”]

Can universities still require slide‑rule use?

Some instructors assign a slide‑rule exercise to build estimation and logarithmic intuition. One poster notes a professor incorporating a slide‑rule project in an online engineering course, then returning to modern tools. [Elektroda, Gregg Williams, post #21663001]

Is mental math still useful if I rely on calculators?

Yes. An experienced engineer reports often rounding and calculating in his head within 10% of a calculator result, using a calculator only for logs. This keeps intuition sharp and reduces over‑reliance on devices. [Elektroda, David Adams, post #21662988]

I learned on tables and semi‑log paper—does that still matter today?

Yes. Skills like reading tables, estimating square roots, and hand‑drawing Bode plots build insight into systems. Several posters reminisce about log tables and manual plotting, which complement modern tools like Excel. [Elektroda, David Adams, post #21662988]