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Empire of the Sum: The Rise and Reign of the Pocket Calculator

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The hidden history of the pocket calculator―a device that ushered in modern mathematics, helped build the atomic bomb, and went with us to the moon―and the mathematicians, designers, and inventors who brought it to life

Starting with hands, abacus, and slide rule, humans have always reached for tools to simplify math. The pocket calculator changed our world, until it was supplanted by more modern devices that, in a cruel twist of irony, it helped to create. The calculator is dead; long live the calculator. In this witty mathematic and social history, Keith Houston transports readers from the nascent economies of the ancient world to World War II, where a Jewish engineer calculated for his life at Buchenwald, and into the technological arms race that led to the first affordable electronic pocket calculators. At every turn, Houston is a scholarly, affable guide to this global history of invention. Empire of the Sum will appeal to math lovers, history buffs, and anyone seeking to understand our trajectory to the computer age.

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Published January 1, 2023

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About the author

Keith Houston

4 books134 followers
Keith Houston is the author of Shady Characters, The Book, Empire of the Sum and Face with Tears of Joy. His writing has appeared in the New York Times, the Wall Street Journal, the Financial Times, Lapham's Quarterly, BBC Culture, and on Time.com. He lives in Linlithgow, Scotland, with his family.

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5 stars
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Displaying 1 - 30 of 66 reviews
Profile Image for Jessy.
55 reviews
November 27, 2023
One of my favorite microhistories in a while! Covers the history of humans using tools for calculations from ancient counting rods to computerized spreadsheets. Some of the chapters about the evolution of relays, transistors, and chips was not as interesting to me, but overall I really liked it. Highlights include learning how to use a slide rule, underpaid women as human calculators, and the history of Texas Instruments' heavy involvement in math education (to sell calculators).

Some quotes:
"One wolf is manageable; two wolves are a challenge; any more than that and time spent counting wolves is better spent making oneself scarce."
"[I]t was without irony that a member of the U.S. National Defense Research Committee could, in 1944, refer to a unit of computing power as a 'kilogirl'. Just as today the word 'computer' puts us in mind of a faceless electronic device, for the male scientists of the era, a computer was an organic, female version of the same thing."
"It is sobering to think that the safe operation of a $24 million fighter jet was largely dependent on the $130 calculator strapped to its pilot's thigh."
"[C]alculators undoubtedly have an important part to play in math education, even it that means suffering the occasional classroom humorist to type out '58008' and turn their calculator upside down."
Profile Image for John Devlin.
Author 124 books106 followers
August 30, 2025



So this is a fine retelling of man’s desire to count, to do math, and to break away from the confines of the Mind.

From fingers, to rope knots, to counting boards, to the abacus, the slide rule, and finally calculators mechanical and electronic it’s all here presented with a breezy readability.

Unfortunately, few political points need to be made
“As if to underscore its utter, inescapable ubiquity, the slide rule was complicit in the dreadful events over Hiroshima, Japan, on August 6, 1945.”
—the bombing of Hiroshima saved American…and saved Japanese lives. So unless the author is decrying the nature of war his comment is misplaced.

Oh and,
“The “girl” was one Katherine Johnson, a forty-three-year-old Black woman, and she was ideally placed to give Glenn the reassurance he needed. In her nine years at NASA, Johnson had coauthored a paper on orbital mechanics that informed, in part, the computer programs that Glenn did not trust. 45 With three days to spare before the launch and an astronaut needing reassurance.”

This did not happen. The movie Hidden Figures was largely fiction and even the book misrepresented the black women computers role in the NASA program.
Profile Image for David.
735 reviews368 followers
July 10, 2024
I love micro-histories, but this one didn't hold my interest. Perhaps the fault is mine. I could not visualize the machines, both primitive and modern, which were described in loving detail throughout the book, on the basis of the text alone. There are almost always accompanying photographs or illustrations, but it is awkward to flit back and forth on the old-school black-and-white Kindle. Perhaps it would be easier in a Kindle app or even in traditional paper format.

What would be ideal, of course, is for the book to be equipped with the far-future technology that I often see on the most recent iterations of the television documentary Star Trek, wherein characters produce a ghostly mid-air holographic control panel for their spaceship by an upward flick of the wrist above the old-school physical control panel. So (in my fantasy example), if you lack (as I do) the abstract visual sense sufficient to understand the textual description (plus accompanying photo) on page 83 of how to manipulate Wilhelm Schickard's Rechenuhr, or “calculating clock”, you could just flick your wrist upward and, viola!, a ghostly mid-air holographic image of the same would appear above my Kindle, where I could poke and swat at it until I fully appreciate the cleverness of this primitive calculator.

I don't get out much, so when this book, in Chapter 7, referred to a 20th-century designer as “the Jony Ive of his day” (p. 138), the name meant nothing to me. In case you are similarly ignorant of Mr. Ive's accomplishments, see here.

I can't help myself. I must point out errors of fact. In this case, on page 153, the author says that early 20th-century computer pioneer John Vincent Atanasoff was a Hungarian American. He was not. He was a Bulgarian American, meaning (maybe I'm getting needlessly specific here) that he was a US-born person of Bulgarian heritage. My source for this information is The Man Who Invented the Computer: The Biography of John Atanasoff, Digital Pioneer by Jane Smiley. I listened to Smiley's biography as an unabridged audiobook during a period when I actually lived in Bulgaria. From this experience, I would advise Keith Houston that, if he ever runs into a Bulgarian who has read this book, he should expect a long shower of opprobrium. They can be a touchy bunch.

Finally, here are some words which appear in this book that I did not know: dreich (p. 55), prostaphaeresis (p. 58), bezel (p. 75), splines (p. 98), piezoelectricity (p. 228), tumblehome (p. 246), and skunkworks (p. 268).

This book was the subject of episode 563 (12 December 2023) of the podcast "99 Percent Invisible", available here.
Profile Image for Kam Yung Soh.
958 reviews52 followers
October 6, 2023
A fascinating book on the history of counting and the rise (and fall) of the pocket calculator. The author starts with a history of humans counting and remembering counted values using various parts of their body. This leads to various ways, like notches on sticks or imprints on materials, as a way to record values. The need to quickly add, subtract and record values leads to arithmetic aids like the abacus and other simple mechanical aids.

The need to quickly perform multiplications (and other operations like division, square roots, etc.) would lead to mathematical innovations. One of them would involve the creation of logarithms, which convert multiplications (and the other operations) into 'simple' additions and subtractions. Various tables would be created before, once again, machines would be created as aids, like the slide rule. Other calculating machines would become more sophisticated, finally culminating in the mechanical wonder, the Curta, a handheld mechanical calculator.

The rise of electricity and electronics would lead to mechanical relay calculators, then calculators based on vacuum tubes and then, individual transistors and those with integrated circuits. The race to cram more transistors and mathematical operations into cheaper, and smaller, packagers would culminate in the rise of the pocket calculator. The pocket calculator race would lead to various wonders, like the scientific calculator, the programmer calculator, graphing calculators. Strange variations would also appear, like watches with calculators.

The book closes with the final 'act' when computers would 'swallow' the calculator by implementing it in software like Visicalc (one of the first spreadsheet software), leading to the world we know today, where we calculate using software and actual calculators now live on a neglected life in our drawers.
Profile Image for Rob Sedgwick.
478 reviews8 followers
June 20, 2023
(Note: I received an advanced reader copy of this book courtesy of NetGalley)

Empire of the Sum will I suspect will appeal most to people who remember the 1970s and 1980s which were when the pocket calculator and its close relative, the digital watch, came from nowhere to become a must-have accessory. Their rise was meteoric, but their fall was rapid too. This book tells their story.

The need to do calculations and keep running totals is as old if not older than writing and the book covers the first technologies to help do maths. Abacus, log tables, and mechanical and desktop calculators are all introduced and explained. I learned log tables at school but never understood slide rules, though I have picked one up more than once long ago. I finally understood how they worked thanks to this book! I loved all the photos in the book, there are some brilliant ones of early devices and machines you will almost certainly never have seen, not least because many of them cost a fortune when they were first on sale. I don't think there was a single photo in this book I didn't spend quite a while looking at.

As computing power increased, the calculator became smaller and less expensive. Vacuum tubes, semiconductors, the CPU and human ingenuity eventually produced a machine that every schoolchild and office worker who needed one could afford. There were lots of people and companies working on the problem and many different products and firms knocked one another off their perches. In that way, it is very different to the mobile phone or PC which were dominated for long periods (and still are) by firms like Apple and Microsoft. But there are names you will still recognise like HP and Casio.

Everyone will reach the point in the book at which their own story begins. For me, it was the early 1980s when digital watches were the must-have accessory at school. I got a 38-step programmable calculator on which I wrote my very first "computer program". It was my pride and joy until I got an actual computer not long afterwards. In reality calculators and watches existed for many years before I was aware of them (I now realise), they were just way beyond the price range of standard households.

Eventually, the computer and then the mobile phone became general-purpose tools powerful enough not to need a separate device to do calculations and the spreadsheet/app saw off the calculator along with similar things that we all used to carry around like cameras, music players and torches. And then newspapers, magazines and books.

Empire is a good book which looks at a neglected area in our recent history. The mobile phone and the computer/tablet were the eventual winners of the gadget race, but the pocket calculator had its day and it still lives on in the classroom. I used both the Windows calculator and a mobile phone calculator app in the last week. As the book points out in its final pages, it lives on in software.
Profile Image for Duncan.
19 reviews
January 26, 2025
This is somewhere between 3 and 4 stars for me. I liked the first half, which basically covers the history of math and pre-modern counting methods, much better than the second half, which covers the corporate race to produce better electronic calculators post-WWII and could be somewhat dry. I do think the author does a good job of showcasing the crucial role that the calculator played in computing history while not just making this a book about the invention of the computer.
Profile Image for John Bravenec.
27 reviews9 followers
March 8, 2024
The first 2/3 of this book were super fun! I had no idea how many mechanical calculating devices were made, and how recently they were still state of the art. Last third was interesting, but in more of a “business wars” sense. Commoditization has consequences.
Profile Image for Kyle.
426 reviews
September 29, 2024
A very nice history of the calculation tools humanity has used since the beginning of history (and a bit before). Houston has very readable prose and entertainingly tells the story of computation from notches on sticks, to abaci (counting boards and counting rods), to slide rules, to the pocket calculator. I am, perhaps, well-suited to enjoying this book given its subject area, and I was not disappointed. I think anyone just with an even casual interest in how people used to do basic arithmetic or the history of the computers and calculators will find this book interesting.

I have no real complaints as I thought the author generally kept digressions short and had a nice narrative flow through each chapter. I will also give some praise to the book as a product itself. It uses color, has a very nice paper, font, and style throughout that I thought actually enhanced the reading experience. The quality of the book and paper from the publisher is noted and appreciated, as well.
Profile Image for Steve.
1,197 reviews89 followers
November 17, 2023
Unexpectedly fun history of calculators. Starts with very early “devices” such as tally sticks, counting boards, abacuses, slide rules. Then mechanical, electrical, and finally electronic gadgets. Very nicely written, with lots of cool pictures.
Profile Image for Amelia.
78 reviews
December 15, 2023
This was not my favorite topic ever to read about, but it was quite well written and I liked the images and design.
Profile Image for Daniel.
588 reviews7 followers
May 21, 2025
Review the history of the calculator from antiquity to the present. I remember getting a Commodore calculator in 11th grade for Trigonometry/Advanced Math as a present from mom and dad.
Profile Image for Sam T.
368 reviews7 followers
September 23, 2024
(Audiobook - 25)

Sometimes you just want to know everything about calculators. Good history, author calls out the bias towards men getting women’s credit
Profile Image for Joshua Qin.
30 reviews
August 16, 2024
EXT. ITALIAN VILLA, 1965. A commercial opens with a woman in a bathing suit, fresh from the pool, sitting down beside a man clad in business attire. On the table is what looks like a cross between a cash register and a typewriter - except it's sexy. It is organic and mechanical at the same time, with gill-like louvres, curved edges, and keys that swell up to meet the fingers like bone beneath the skin. It is the Olivetti Programma 101, the most exciting calculator in the world, and it is an imposter.


So reads the intro of Chapter 9. This is one of my favorite passages, but it's really emblematic of the sort of beautiful way Houston is able to convey his story. Even for something as mundane and as niche as the pocket calculator, Houston is able to craft an incredible novel full of vivid imagery, wit, and charm.

The book gives detailed description of each inventors character and relevant life stories, their thinking and processes, to really effectively show how human calculation evolved from counting on your hands to graphing calculators and spreadsheets.

I genuinely can't imagine how anyone could write a more interesting book than this on the history of pocket calculators. If you have any interest in computing history, I strongly recommend this book.
Profile Image for Domenic Boscariol.
36 reviews1 follower
March 7, 2024
Very interesting read, reminded me of the calculators I had in life, starting with a TI-58C that I got as a high school graduation gift, which was my companion through Engineering studies in university.
368 reviews1 follower
July 24, 2024
As a kid, my dad took me to his office once in a while on a weekend. While he worked, I played with the machines. I was allowed to make one or two thermofax copies--they were expensive! Then it was on to the huge, gray adding machines. The first thing I always did was push all of the 9 buttons, then push all of the 9 buttons again and add them. Disappointingly, the machine didn't expire in a puff of smoke. However, it gave me valuable experience in getting the wrong answer, a lifetime skill.

Moving ahead to 1970, a friend bought one of those fancy new tech contraptions with the incredible visual display: a calculator. They cost about $400. His dad scoffed, "$400?! They'll be giving them away with a tank of gas."

He was wrong, but not about the price of calculators; the price of gas.

This book traces the rapid rise of calculators and 30 years later, their disappearance. (Not their extinction--they're still around, forgotten and dusty in kitchen junk drawers everywhere.) Before computation, there was counting and keeping track of numbers. The earliest known tool was a stick with notches cut into it. Then came markers of different shapes signifying denominations. Moving into calculation, markers were placed on grids drawn on a table or in the dust. The markers were moved to represent addition and subtraction. The equivalent tool was the abacus, which had the advantage of being portable. In the 1500s and 1600s, there was a fascination with clockwork mechanisms for timekeeping, toys, and mathematical calculations. They were cool but hard to build, temperamental, and expensive.

When electricity became available, the invention of relays--mechanical switches that received and dispatched electrical signals--opened up a world of computation possibilities, but relays were bulky and prone to mechanical breakdowns.

The answer to those problems was vacuum tubes, then transistors, then computer chips. Chips were capable of doing so much more than calculation at little if any extra cost, and that was the end for calculators.

The writing is pleasant in an understated, British way, but I became bored with the technical descriptions. A few pearls:

Why did we need transistors? One example: We had 4000 B-52 bombers in 1954. Each one had a fire-control system that included 1000 vacuum tubes.

Transistors were too durable for manufacturers' tastes. They could operate for 20 million hours. The first opportunity for a replacement sale would be in 2000 years. Pat Haggerty, the visionary CEO of Texas Instruments, had the answer: Mass appeal products requiring transistors. TI RandD'd transistor radios and promoted them tirelessly.

When a similar problem arose with silicon chips, Haggerty embraced calculators. And TI calculators became legendary.

It was so easy to create multi-talented chips that some weird combination products were offered: Calculator/clock/radios, calculator/Dictaphones, calculator/music synthesizers, and calculator/cigarette lighters. They had some great names, too: Compuchron, Timeulator, Pocketronic. And the Pulsar Time Computer Calculator, an enhanced wristwatch that was as clunky as its name.

Profile Image for Bookworm.
2,316 reviews98 followers
December 11, 2023
I am young/old enough to remember what was like to learn about how to use a pocket calculator, including writing simple messages and doing silly things with calculators we had in class. It seems a little quaint now, with teachers telling us that calculators would not always be there and we would need to know how to manually calculate these formulas. Well.

In this microhistory, author Houston takes us through calculators through history, starting with our hands to calculators. Obviously as time passes there is need for a machines and calculators that can handle more and more complex equations and concepts. Each chapter is dedicated to a certain machine with its history, impact, its place in society, etc.

It was kind of dull. While it was interesting to look at something that used to be fairly common in schools, and how the advancement of technology has made it unnecessary for many people to even remember algebra, etc. it was not as compelling as I thought it would be. In some ways it felt like it would be better as a long read in a magazine or magazine, rather than a full book.

Still, when considered in the context of AI all, this was still useful. I do think it is a good book to read for certain people: if only to remember what we came from and how and what it took to create technology that can perform lots of these calculations for us. Ultimately it felt skippable, but for those interested in microhistories, in calculators, one aspect of math, etc. this might be a good book.

Borrowed from the library and that was best for me.
Profile Image for Popup-ch.
899 reviews24 followers
January 2, 2024
The history of the pocket calculator status with the history of pockets (the earliest preserved pocket belonged to Ötzi the Iceman) and calculation (enumeration and comparison go back a long way), but the bulk of the book focuses on modern aids to calculation, such as the slide rule and mechanical means, such as the marvelous Curta - arguably the first pocketable calculator, even if it only really could do addition and subtraction.

The first electronic calculators (the relay-driven Casio-14A, and others) were desk-sized, rather than desk-top tools, but smaller versions came with transistors, and ultimately the integrated circuit. The Intel 4004 was an early marvel and even if it only could do abortions and subtractions, combined with a ROM containing simple algorithms, it could perform almost instantaneous multiplications and divisions at the press of a button!

The first serious scientific calculator was the HP-35, developed as a skunk-project endorsed by Hewlett, and sold in in the millions straight to consumers, rather than through the scientific equipment channels.

There's also a fascinating excerpt from the history of Olivetti, who produced the worlds first desktop computer, only to go under in a series of question marks. (Was the CEO killed by the CIA? Did IBM steal the blueprints? Who killed the CTO?)
412 reviews15 followers
September 20, 2025
I was expecting a book that was more calculator focussed, perhaps misled by the sub-title. This is a book about pocket (and other) calculators, but it's more a book about calculation and its mechanical assistants, from the abacus and Napier's Bones through to computers.

And that having been said, it's a great history. It addresses the needs that have driven mechanical computation over the centuries, as the applications have changed alongside the technology (and in many ways have driven its development). You can see this in the way that the scale of the machines changes, becoming alternately smaller and more pocket-sized and then larger as the increasing demands require steam or electrical power. (The latter can be miniaturised while the former clearly can't.)

What we would actually regard as pocket calculators occupy only a tiny part of the story. I think there's a more detailed history that could still be written about the different processors used, methods of entry used (for example HP's determined and continued use of reverse-Polish notation), and how these were taken up by sub-groups within science, engineering, and finance and used almost as tribal signifiers ("real engineers use HP"). But that would miss the wider story that this book tells well.
209 reviews1 follower
September 17, 2024
A delightfully nerdy, very detailed history of the calculator told in a popular non-fiction style. Houston runs from the origins of counting and base systems to abaci, slide rules, and all sorts of calculators from mechanical to graphing. Along the way, he tells a broader story of the technologies behind most of our gadgets, from relays to cathode ray tubes to transistors and integrated chips. I was amazed at how fast calculators accelerated in speed, cheapness, and function once they were developed. There's some fun side stories about unnecessary calculator combos (there was once a calculator that doubled as a cigarette lighter!). The book really emphasizes how technology and knowledge have been accumulated by thousands of people around the world over millennia. My favorite was that ancient Egyptian algorithms for multiplication turned out to be a much more efficient way to program a calculator to do multiplication than more modern methods! Definitely check this book out if you're a tech/math dork.
Profile Image for Behrooz Parhami.
Author 10 books35 followers
December 31, 2023
Many members of my generation owned and admired their electronic pocket calculators, which, after dethroning the engineers' slide rules, were themselves unceremoniously replaced by much more powerful computing devices. Nevertheless, calculators did play an important role in the development and history of computing. I have fond memories of my very first electronic calculator, the fairly affordable HP-35, which I bought in 1972 during my grad-school days at UCLA.

Beginning with a history of counting and ancient calculating devices, Houston tracks down the origins of the modern electronic calculator, along with some interesting detours, like how Texas Instruments hijacked high school math curricula across the US by promoting its outdated calculator lines that were highly profitable.
Profile Image for Sanjay Banerjee.
542 reviews12 followers
September 8, 2023
As the name suggests, the book is about the history of using aids for calculating from historical times to present day. The trivia from historical times was interesting as was the initial history about the development of various technologies - mechanical, relays, vacuum tubes, transistors, chips - as was the development of various models of calculators. Also interesting were the trivia about the history on origins of various companies like Casio, TI, HP, Fairchild, Intel etc. the book is about the history of a product which is now obsolete and exists more as an App on your phone, tablet or computer.
2,323 reviews2 followers
February 16, 2024
A good book but the title is a bit of a misnomer. The history of calculation is good, and that makes it a fun read; but the pocket calculator is only a small part towards the end. The author could have spent a bit more time on it and the types. I began to learn how to use a slide rule just as the pocket calculator came out and I have worked in computing since the early 1980s, so I did find the swath of history to be enjoyable.

For me, someone who has been in computing for a long time, I had problems with some of the errors in those last segments. For instance, he talks about the PDP-10 being huge. Nope. Not close. It was a mid-size, nothing such as a 370/3033.
Profile Image for Tomas H.
15 reviews
November 28, 2025
A book about the history of calculators??? Is this a joke where you’re trying to invent the world’s most boring book idea? Well … no joke, this book is as relevant as it is insightful to how innovation and technology progress in culture, education, fads, business … you name it. The calculator as a machine to offload mental space is for example the perfect stand-in for the current evolution of AI as I type this. Understanding the long timeline of counting machines from rocks and sticks to abacuses and slide rules, to mechanical counters and the transistor revolution … these shifts all likely contain echoes of our imminent ubiquitous AI facilitated future.
Profile Image for Lisa Yee Swope.
365 reviews4 followers
November 16, 2023
My dad taught me trigonometry on a corded scientific calculator that used reverse Polish notation. He was so proud of that calculator, which he bought, at great expense, as an early adopter. He never stopped marveling that I had a pocket scientific calculator in middle school, and a graphing calculator in high school. When your children need the latest and greatest from Texas Instruments, please think of my dad, and be glad for our future. We sent people to the moon using slide rules, peeps.
452 reviews2 followers
January 29, 2024
What a fun book! If you have any gear geek tendencies, you’ll enjoy this book. If you’re only interested in the technical history of numbers, counting, and calculating devices, you’ll enjoy this book. On top of the technical and historical documentation—which is heavily researched—Houston has a sense of humor that permeates the text and made me chuckle frequently (beware that some of it is geek humor). Lots of images of counting and calculating devices, including one of my old-time favorites, the Curta mechanical calculator.
Profile Image for Brooks.
182 reviews6 followers
November 2, 2023
Great book, I am going into the garage to see what kind of old school calculators are in there ... fingers crossed for a HP 35! Well told story about the history of calculators, as such ... you wouldn't think it would be that interesting, but was well told, and explained. It made, me the reader, want to get down in there, and do some tear downs on these old school calculators!! Next stop ... that kitchen drawer, with the old calculators!!
624 reviews
July 14, 2024
This was not what I was expecting. Only a very small fraction of this book is actually about the pocket calculator. Instead, it's a history of devices that humans have used to aid in their calculations, starting with counting knuckles, to the abacus, clockwork adding machines, slide rule, and finally to the developments in the 20th century that resulted in the pocket calculator. Fascinating, especially the bits about making the math work.
857 reviews6 followers
Want to read
December 15, 2023
Added this in December 2023.
Podcast - 99% Invisible #563 - Empire of the Sum - pocket calculator
Keith Houston wrote about the evolution of the calculator in his latest book, Empire of the Sum The Rise and Reign of the Pocket Calculator. It is exactly the kind of nerdery we like to get up to here at 99% Invisible -- history explained through the lens of an everyday designed object.
Profile Image for Rayfes Mondal.
447 reviews7 followers
January 15, 2024
A lot has been written about the history of computers but this book is about the history calculation and the rise and fall of calculators. I had many calculators growing up so this was interesting to me.

My only beef was that the vastly superior HP calculators should have been covered more. Sorry TI fans. I still use an HP 48 emulator on my phone. RPN FTW
Profile Image for James Biser.
3,795 reviews20 followers
April 4, 2024
This book gives an excellent review of the counting humans, mathmeticians, and business people who have worked for centuries to create tools to help the world do math. Although it may have started with bones, sticks and stones marked for counting, it evolved into the abacus, slide rule, and personal computer.
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