Ask HN: Should there be new RPN calculators to replace the TI-84?

TI calculators are not RPN. I think HP made (makes?) RPN calculators.

Calculators, especially scientific and graphing calculators, are a niche product these days, almost exclusively limited to education and exam-taking. There is no impetus for changing the approved models, given the mountains of materials adapted to their use (TI actively worked with various educational bodies to promote the use of graphing calculators and helped prepare the curricula using their own.)

Don't expect great changes in this area, although the impending death of the Dept. of Education might shake up things. Not for the better, I think.

Even 7th and 8th grades use TI Nspire CX calculators in my area.

As rightbyte said, RPN is an HP thing, so if you want an RPN calculator, ask for an HP. Most test administrators can help you.

Have a look at https://www.numworks.com a easy to use scientific calculator that is opensource

There are some RPN calculators from SwissMicros that are inspired by HP’s RPN calculators from the 1980s and 1990s:

https://www.swissmicros.com/products

There is also the HP-15c Collector’s Edition (I have one), which is still in stock: https://www.thecalculatorstore.com/c/hp15c

Two caveats:

1. These RPN calculators are not cheap.

2. Many standardized tests have lists of approved calculators, and it’s possible that the calculators I mentioned might not be on the list. TI has dominated the education market in the United States for the past few decades, and even during the heyday of HP’s RPN calculators, HP largely focused on engineers and other professionals rather than education. Thus, you may need to buy a TI calculator for exam purposes.

I love RPN calculators: I have a HP-48X that I bought used on eBay nearly 20 years ago when I was an undergrad, and my aforementioned HP-15c Collector’s Edition. However, these are collectibles for me; as a computer science professor I’m always in front of a computer, and thus I have access to the Unix dc command whenever I need an RPN calculator, and for more complex computations I have my choice of Excel and various programming languages.

The HP Prime, though pricy, supports a decent RPN mode. Definitely for a higher level of education (CAS, programs, all that fun stuff), but approved for a decent amount of US based exams.

I had to look it up:

RPN = reverse Polish notation

https://en.wikipedia.org/wiki/Reverse_Polish_notation

Wow. In my day it was well-known. HP calculator ads in magazines explained RPN and why it was better.

"Magazine? Had to look it up."

Not what the OP asked for but related.

The link below is for a near perfect simulation of the classic HP-15C RPN calculator. Works on both desktop and mobile.

In a former lifetime, I was an engineer. I bought one of these in the early 1980s and used it for almost 40 years before the screen died. Very popular among my colleagues at the time.

https://jrpn.jovial.com/

That is awesome. Thank you for posting this.

I did UIL competitions in Texas in the late 90s and early 2000s, including calculator competitions.

That's the only place I've ever heard of RPN, which is what nearly all of the winners used, and which we learned to stand a chance.

Not really true anymore unfortunately: The latest models (post-2020?) are locked down and cannot use non-official FW.

As a high school student I can’t recommend the NumWorks enough (but you will absolutely find it lacking if you need it for anything other than high school maths).

It’s a really nice tool (although not an RPN calculator). It’s like if Apple designed a calculator… very intuitive.

That said, I wouldn’t call it fully open source. They had some issue because they released an update that locked down their calculators to satisfy school boards (because otherwise students could modify test modes to cheat on tests). The software on GitHub was also out of date, last time I checked.

Good to know, while I had purchased one for my daughter, I had only a cursory look at the released files.

No. They're all ganked to be permitted on standardized tests anyway.

>Should there be new RPN calculators to replace the TI-84?

I'm not sure I really understand your question, TI-84 (and all other TI models) don't use RPN. You can run a program to allow RPN input you want, since most of the higher TIs are programmable. I believe some of HPs current lineup have a limited RPN mode available and SwissMicro makes some new RPN calculators.

>I took an exam today where only TI calculators were available.

That's common as they are the ones used to teach math classes and are vetted to prevent cheating on standardized tests.

>I felt I was caught between some older models where the TI interface was not quite worked out.

I have no idea what this is supposed to mean.

>And I don't see much progress then trying my daughter's TI-84.

Nor this.

>RPN is an HP thing

Not anymore, that's why older engineers pay inflated prices for old ones on ebay.

Or pay extra for https://www.swissmicros.com/products

Sadly my HP 48G is dead dead (water damage and corrosion) and they don't have a replacement for that.

The DB48X project looks interesting: https://48calc.org/

What is lacking from the TI-84? Why do you specifically want RPN?

Pricy is relative. Looks like Amazon sells it for $125 (the SRP is $230)

As an engineering student in 1987, I bought a HP-28C. I recall it was the first calculator to do symbolic math

Original Price $235 which is close to what I paid. Adjusted for inflation $657

I think it was worth it.

Having been the proud owner of a TI-82 myself I can only surmise this guy has no idea what RPN means

Need to find one of these for hp32SII

I waddled into my first UiL calculator test because the sponsor wanted to get more team members and spent most of my time blown away watching kids entering problems into two calculators simultaneously

Not sure I remember my TI-84 being RPN

Swiss Micros have some fairly decent recreations of HP's greatest hits. Pricey, but I am going to get myself one for my birthday. https://www.swissmicros.com/products

As a Middle-Aged person who does math on the periphery of calculus reasonably often, for work and in my day to day life, my irritation with calculators is that their capabilities are largely driven by the education markets demands. The small handful of calculators with CAS abilities are usually kneecaped to what would be allowed in a testing environment.

I want a calculator that can do all the transforms for me and show the work so I know what I'm doing.

For my day-to-day needs I literally run a TI-89 emulator on my android phone these days. Seems silly.

Yeah, I'm also confused by this... the only RPN calculator I know of is the HP 15C, which is old school and not used in education.

I know they removed the CAS capabilities to appease school boards. Are you still able to replace the firmware with the CAS capable version?

Back in college one summer, I had an HP calculator crammed full of programs I had written for various circuit and RF design courses I was taking. I didn't have any way to store them, other than writing them down on paper. On a whim that summer, I went to take the Ham Radio Extra class exam one weekend. The proctor said I needed to erase all the memory from my calculator before using it on the test. I told him no way was I going to do that, but suggested an alternative.

I had been curious how slide rules worked, and had found one after searching high and low for in half a dozen stores before finding probably the last one for sale in Atlanta. The slide rule was in my backpack, so I asked the proctor, could I used the slide rule instead? He chuckled, and said no problem. During the test, one of the proctors tapped me on the shoulder and asked me if he could bring me a bucket of water to cool down my "slip stick". I did pass the test that day, and I used to brag that I got my Extra Class license with a "Slide Rule endorsement".

So far my son (8th grade) really just uses Desmos https://www.desmos.com/calculator which is apparently also built-in to the SAT now (which is taken on a computer) - I have been trying to convince him a separate calculator is better but so far no luck.

I have several of these and I'm really impressed with the quality. The DM32 is nice and has a manual available from SwissMicros, but I prefer the DM42n. I had a print shop print and spiral bind an HP-42 manual for me. Works good.

I think there may be some confusion about "RPN" (Reverse Polish Notation). It was very popular with certain folks, Back In The Day, but I, personally, never warmed to it. I don't think it ever would have been mandated for tests. It was very much a "deep geek" notation.

But if you really want it, and are an Apple user, I have found that the PCalc app[0] has been excellent (I've used it for over 30 years). It works on multiple (Apple) platforms, and has RPN (the real RPN) built in, as a selectable option.

I suspect there's similar apps for Windows, Linux, and Android.

[0] https://pcalc.com

If you want a native options on a mobile device, Free42 and 48sx work great on Android (I believe at least Free42 is on iOS). Emu48 works on desktop (personally I like `dc`). Look at SwissMicros if you want a physical calculator.

I bought a HP50 (?) in uni to do symbolic math for some exam. It was RPN by default but you could switch.

> HP 15C, which is old school and not used in education.

Business courses frequently use it

IMHO we'd be better off focusing on policies that allow computers to be used on standardized exams. Hardly anybody uses a calculator in a real job, people at desks use computers, and even people who have to do calculations in a field environment use ruggedized tablets. Rather than working on revamping obsolete technology we should work on a way to make a computer acceptable to use on an exam in a way that addresses cheating concerns.

But if you really wanted to keep using a calculator, you should check out the HP Prime, Casio Prizm, or TI-Nspire series. The HP Prime has RPN, and all of these lines have color touch screens and a bunch of modern features. The TI-84 is not the pinnacle of technology, it is popular only because it is an exam-acceptable and an old standard format that people are used to.

Education seems to be moving to computer based systems like GeoGebra and Desmos. So the market for separate calculators is becoming even more niche, mostly just die-hard fans who'll get stuff like SwissMicros devices

You still see some HP12Cs on bank trading floors.

When I was in high school in the 1980's, the other students knew RPN only as the reason they couldn't borrow my weird calculator.

I still have my old HP48GX, but I find I use iHP48 more often because it’s much faster. I had a 49G also but the keyboard died just from sitting in a drawer… the HP build quality took a nosedive in the late 90s.

RPN is not a good fit for the classroom. It doesn't connect to the way math and arithmetic are taught, since ages. RPN comes from the days when parsing an expression in a calculator was hard. I've got a two RPN calculators at home, and I think it's cute, but it's a nerd thing.

If you want a non-TI calculator that's allowed in the classroom: look at the Casio and Numworks.

Mathematica?

I'm a for-funsies pilot and I took my most recent exam with a physical EB-6, which is a circular slide rule of sorts. Of course the way people take these exams these days is to just to memorize all the questions. The FAA hasn't seriously updated the question bank in years and there are known wrong answers in the answer key.

Inflation adjusted they are cheaper than the HP they are recreating. Even if you don't adjust for inflation they are competitive to the old HPs in the 1990s.

The only real place I've seen RPN calculators used post-2000 is in calculator competitions (oh yes they exist)

I use numworks frequently these days (as a software eng just need to do some quick math and not worth writing code or spreadsheet for, not talking about student use). I bought the thing but they have a free phone app too, works exactly the same.

I can't ever remember how to use my TI-89 but the numworks is pretty intuitive

What are you testing? I found in math that my test scores went up when I quit using a calculator. All the exam questions were carefully designed to make the arithmetic easy if you did it right. Thus anytime the arithmetic looked hard I knew to start over and find/fix my mistake.

In physics that didn't always apply, but it did often enough that I didn't pull out my calculator until after double checking that I was sure I did all the steps right.

In engineering classes the math was never easy. In the early classes you should still use a basic calculator though as the point is to understand the math behind the problems. In latter classes you can be assumed to understand that and computers to do all that complex math while you focus on the large problem might be good.

> the Dept. of Education might shake up things. Not for the better, I think.

Given how mediocre and even harmful public education in the US is, especially relative to its (now waning) superpower status, how large the US is, as well as the promotion of weird ideologies by the DoE, I cannot help but welcome its death. In general, I welcome to end of all sorts of vast educational bureaucracies, including those that have occupied private universities and drain them of resources without providing any justifiable benefit.

I think this is where people don't grasp that we didn't always have the kind of overbearing, cabinet-level department of education we have today. This really only goes back to the early 80s. Meaning, opposing the DoE isn't the same as opposing education. The principle of subsidiarity ought to be respected. Decentralization is good. It should be liberating.

So, in practice, I anticipate a greater diversity of curricula. There already exist competing views on pedagogy. This would allow greater flexibility and educational liberty, but also the opportunity to observe how well various pedagogical approaches work. It also introduces a certain accountability, because while you can blame mediocrity on a distant DoE today, the responsibility for education will lie closer to home when there is no DoE to blame.

Incidentally, people like Feynman ostensibly lamented that he expected physics to stagnate given what he saw as the homogenization of education. A similar principle could be said to apply here.

HP 50g is "modern" and has RPN out of the box, I use it regularly.

The TI-84 is not an RPN calculator. But what would be the advantage?

And what is this "progress" you speak of? Frankly, I don't know that these calculators should be used in instruction anyway. It smacks of attempts to "modernize education" by throwing computers are it, without justification. Why? Computing devices have their place, but their utility is practical, and their pedagogic value in primary education is limited to specific applications. Using them to teach math seems off. You shouldn't be wasting time on things that have little educational value but that would require a computing device to expedite tedious work.

If you want a truly native option, a small run of HP-15C calculators was manufactured a year or two ago and you can still get them:

https://hpcalcs.com/product/hp-15c-collectors-edition/

I bought one and am happy every time I use it, which is quite often.

There are RPN input programs for the TI graphing calculators.

There are RPN calculator apps for phones (I like RealCalc on Android).

There are RPN calculator programs for computers (I like Qalculate for GUI, Orpie for a terminal).

There are emulators for the old HP RPN calculators.

Physical calculators are pretty much only useful for situations where internet access isn't allowed, like some exams in school.

Thanks for the heads up! Just ordered one.

OP's question wasn't about whether they should use a calculator on an exam or not. If you can trust that an exam has questions crafted to have integer answers and completed only with basic arithmetic, then use that strategy by all means.

OP's question was whether or not there should be replacements for the TI-84, and mentioned that this question arose from an experience taking an exam. Aside from the fact that they may be confused about what RPN is, I suggested that I would consider the use of computers a better focus for exams rather than getting a replacement for the TI-84. And aside from that, there are already replacements in the forms of new calculator product lines.

The correct answer depends on the exam's goal. If you want to verify understanding the fundamentals, then a pencil and paper is all you should get. However that limits the complexity of the problem you can be asked. With a calculator you can do more complex problems - but the tool will do some things for you and so if you get the answer wrong there is no way to know if you failed on the fundamentals (you need to drop out of this class and be send to the lower level one) or the complexity (stay in this class).

> as well as the promotion of weird ideologies by the DoE

What weird ideologies?

PCalc is indeed excellent.

As for RPN, it's one of those things I didn't get until I was in my 30s and started using it. Then used it more. And now I'm at the point where using a "normal" calculator is a frustrating experience. I got very used to the stack and having intermediate results. I find it highly frustrating that the windows calculator still doesn't have it as an option, and that when asked about it the developers seemed confused why anyone would want it.

Free42 has filled the gap though.

The E6-B is what I took my exams with too! But, that was ‘several’ years ago.

From my college experience I never needed a Ti or Hp calculator. Most of the questions did not require anything more complex than logarithms, exponential, root and trigonometric functions. A good question should be about concepts, not results. I remember a linear algebra test in where you had to solve a problem by inverting a matrix to get a result, the problem was that the matrix was so large that it could have taken the entire test time to get the result if done by hand. However if you were clever, and knew the matrix properties being tested, the matrix could be simplified and the result gotten in 3 steps. If you had a Ti or HP you could have entered the matrix and get the result, but the question would have lost its meaning

“TI’s calculator ecosystem facilitated a needed educational reform and created training resources for math teachers. Its emergence as a national standard simplified math education, reduced teacher training costs, and contributed to teacher job mobility. Educators, who may have taught for decades, even preferred the lack of innovation. Additionally, students have been able to take standardized tests and enroll in STEM courses in college without needing to switch calculators.”

https://www.promarket.org/2024/04/08/tis-calculator-monopoly...

(Also, TI supports RPN. It also supports PN and infix notation.)

I'm still more of an HP-41 fan.

In addition to having several of these, I also use this desktop emulator:

https://nonpareil.brouhaha.com/

I have used Soviet RPN calculator at my school years. It was not compatible with TI or something Western, but as I know ideologically it was very close.

What also interest, in early 2000s, Russia made modern remake, with much improved performance and added digital i/o, and compatible with old programs (even emulated some old glitches), so it could really run tons of programs one could find on old books/magazines.

I could not recommend anybody to buy Russian calculators, just want to say, this is very significant niche (RPN), but hugely depend on compatibility (with old software and old books) and on nostalgia.

https://en.wikipedia.org/wiki/Elektronika_MK-61

I remember. There was relative of MK-61, nearly fully compatible and in theory have extension port:

https://en.wikipedia.org/wiki/Elektronika_MK-52

And sorry for Russian language link, for some reason I have not found English.

https://ru.wikipedia.org/wiki/Электроника_МК-161

https://web.archive.org/web/20140202161045/http://mk.semico....

I used the TI-85 back when dinosaurs walked the earth. I still have that and the TI-92, the best FAT calculator ever. This thing will tie your shoes and help fight off depression. I strongly recommend the TI-92. It is not allowed on any standardized tests though.

I do know that even my TI-85 was programmable. I made a few different functions with it. If you try anything too sophisticated, there really is not sufficient space for it, but it was the first device I ever wrote any kind of program on. I used that through university, but for work I had the HP 12c with reverse Polish notation. Now that was useless. I could never understand why old men preferred that to Excel. Excel is better in every way, and one can write pretty sophisticated functions and simulations in Excel VBA. I spent years doing so.

Overall, I do not see the point in bringing out new calculators. I do think the existing ones should have more RAM and storage with a bit more computational heft, but only 1-3% of owners are ever going to use that, but it will make them so much better.

That rabbit hole will make you angry, then sad, then hopeless. I live in Chicago, on the South Side. The number of foolish fads in education have been forced on poor children for decades. It is shameful. Children should not be experimented on because their parents could not afford Catholic school or a house in the suburbs. Rich white people enjoy warping the minds of black children far too much. They never experiment with their own children, only ours. It is sickening.

An example: https://www.insidehighered.com/news/quick-takes/2023/09/08/c...

https://www.nytimes.com/2022/05/22/us/reading-teaching-curri...

My thought exactly, or Maple, if you are one of THOSE people.

It's a lot of money and isn't a standalone device.

For many business-type courses they like you to be able to quickly get an IRR or NPV value. One could solve that by hand, but the exams would be long and require manual grading. According to my older colleagues when I started my career, they used to bring their HP calculators to client meetings before laptops were a thing. They would sit around and do estimated calculations. If you look at old photos, your can see the HP calculators in them and paper with written calculations. When I started my career in 2000, laptops were already ubiquitous. There were still old timers with the RPN calculators from HP. Excel is better for finance. For real analysis and simulation stuff like Mathmatica and Maple are better, with SAS, SPSS and R for statistics, although SAS is used a ton in finance, insurance as well as government.

If you want to get REALLY angry, go to school in poor neighborhoods and watch teachers "teach" children how to search the web. Computers in schools was a mistake. If there were to be computers, they should all be Unix or Linux or BSD distros run from the command line.

There are key phrases that a school is scam central. Any time they try to say "X percent of students went off to college" that school is a scam. If they speak of creating "computer literate" or "technology literate" students, the school is a scam.

Check out how easy many of the reading and math tests are, then you will know how horrible it is when schools only have 20-30% of students getting to their grade level. It has been a bizarre transformation where schools went from being oriented around student learning to being oriented around teacher wellness and teacher preferences.

We should be hiring teachers from Singapore and Hong Kong to fix our schools. Instead we hire creepy education consultants that get rich peddling idiocy. It iw a crime against children.

That's another point, during college some tests were and multiple choice questions. They were manually graded and for each answer you needed to prove how did you get the answer. I don't remember any kind of automated grading system. Everything was done by hand, whether by the teacher or TA's

I am a decidedly non-mathematical/non-engineering person, but have loved RPN calculators since I bought an HP back in the mid-1970s. RPN is just natural to me, even doing basic arithmetic. I use PCalc in RPN mode on my iPhone.

I don't see how the DOE promoted this woman's style? It seems like cities and districts independently chose to adopt her methodology.

> I think this is where people don't grasp that we didn't always have the kind of overbearing, cabinet-level department of education we have today. This really only goes back to the early 80s. Meaning, opposing the DoE isn't the same as opposing education. The principle of subsidiarity ought to be respected. Decentralization is good. It should be liberating.

You dumped a lot of vague buzzwords but you said nothing of substance. You oppose DoE? Why, exactly? It's not clear. If you cannot even express why exactly you oppose the DoE, what does decentralization mean, and why do you believe that to be liberating?

There seems to be a segment of the US population that was heavily indoctrinated into an irrational belief that having any guidance at the federal level is inherently a major problem.

In the meantime, back in reality, the main responsibility of the DoE is to fund scholarships and schools from districts that are unable to self-fund. That's what you get rid of when you argue for getting rid of the DoE. Why is this liberating?

Nice… I actually still have a couple, but that’s a nice looking upgrade

These programs were in place in D97 in Oak Park, a wealthy and predominantly white suburb, too.

I've long been a fan of HP Voyager series calculators. I used an HP-11c daily at work years ago. I still have it, an HP-15c, and and HP-12c. The 11c and 15c are both probably still on their 2nd set of batteries, after 40+ years.

Programmable calcs were banned when I went to school since everyone was cheating with them. People even had programs to simulate the clearing of memory.

Oh that is cool to know, thanks.

Most of our professors did allow them. As they explained their reasoning, the information you could store in your calculator memory at that time was roughly equivalent to what you could write on a single piece of paper. So they would usually allow either a cheat sheet or a programmable calculator, and designed the tests accordingly.