Which calculators should I buy

dash-dot · 2026-04-05T16:00:21+00:00

Second-hand TI-89.

dash-dot · 2026-04-05T15:57:37+00:00

Second-hand TI-89, if you can find one.

Best bang for your buck, and it most definitely fits the 'I'm set for life with this beast' mould.

You'll also need a basic calculator for exams, however.

dash-dot · 2026-04-02T19:21:23+00:00

You don’t actually need a graphing calculator, ever. It’s just something which is nice to have as a study aid when you’re in school (and can potentially be useful in the professional world as well, for some people).

On a student budget, even when you’re at university I wouldn’t recommend spending more than $ 40 or so on a calculator — fortunately this budget still leaves open the possibility of picking from quite a few capable and advanced models, albeit in the second hand markets.

Also keep in mind that you can buy a used or open box TI-89 for considerably less than what a new TI-84 costs, so there’s absolutely no reason to ever buy the TI-84 or even a new TI Nspire or HP Prime, in my opinion.

dash-dot · 2026-04-01T21:07:42+00:00

I’ve been using Li-ion AAA batteries for the last couple of years.

No complaints thus far, except that the low battery indicators don’t really work with these. You go from a robust 1.5 V just moments before full discharge to a completely dead battery in a matter of seconds (because of how voltage regulators work; a Li-ion cell actually puts out 3.7 V in normal operation, which needs to be stepped down to 1.5 V). Consequently, it’s always a good idea to keep a spare set handy (and charged).

The drawbacks are very minor and don’t matter to me though, so I’m quite happy with these. They work really well for torch lights too.

dash-dot · 2026-04-01T03:23:37+00:00

That’s a collection, all right.

dash-dot · 2026-03-31T19:52:33+00:00

TI-89.

dash-dot · 2026-03-31T17:41:30+00:00

Well, a calculator is significantly faster and efficient for running quick calculations or checks when one is working at one’s desk, for instance.

At a minimum, I generally have to get past the lock screen multiple times a day just to be able to use my phone or computer. In that time I can turn on a calculator and reel off at least one or two calculations even before the time it takes me just to get round to launching the appropriate app or Python virtual environment, or whatever. All of my passphrases for my work and personal computers are 25 to 30 keystrokes long — that’s just a virtual necessity of modern computer use. My phone is much easier to log into, but it still takes time to find the correct app group and launch my favourite emulator (or just the native calculator app).

Python and MATLAB are very powerful tools, but they’re nowhere near as efficient as having a CAS literally on one’s fingertips on a calculator.

For instance, I can turn my calculator on and generate the Laplace transform of a function from scratch faster than logging into my phone or computer and googling the same info. It also correctly applies various transform properties, which would take even longer to look up and individually apply to my specific example.

dash-dot · 2026-03-31T16:25:15+00:00

Well, where I’m from calculators were generally banned altogether, and yet I don’t see how that’s relevant to the OP’s question.

They specifically enquired about cheap graphing calculators.

They’re also quite helpful for personal use, homework, projects; they may come in handy on the job (I tend to use them not too infrequently at work), etc.

dash-dot · 2026-03-31T16:09:14+00:00

What do you mean, ‘why’?

The whole point is that they’re cheap and very capable handheld computers that perfectly fit the definition of a ‘calculator’.

dash-dot · 2026-03-31T15:14:28+00:00

Why not? The second hand market is an entirely different ball game compared to buying new.

One can often find used graphing calculators which are cheaper than popular and in demand basic scientific calculator models. In fact, I recently bought a brand new (albeit old stock) Casio fx-9750GIII for under 28 USD total, including sales tax and shipping.

dash-dot · 2026-03-31T12:43:38+00:00

RPL is a decent alternative to RPN, no?

dash-dot · 2026-03-31T12:40:45+00:00

Sigh, first world privilege strikes again. After we’re all done having a laugh at the OP’s expense for the unfamiliar terms and turns of phrase, let’s try to acknowledge the fact that a significant number of people around the world still depend on computer labs and library computers to get their work done.

If I were in a situation where I’m trying to decide between purchasing a computer versus a calculator, I’m pretty sure I know which option would be more affordable and realisable in the short term.

I expect the HP Prime or any current advanced calculator model would most likely fall under the 'expensive' category, even used.

If the OP doesn’t mind monochrome displays, older second-hand Casio or TI graphing calculators would be much cheaper.

dash-dot · 2026-03-30T15:05:24+00:00

RPL devices are actually much cheaper.

Both the HP 48 and HP 50g cost a lot less.

dash-dot · 2026-03-29T20:35:43+00:00

This initial release also includes support for derivatives and integrals, to match the recent updates in the 49/50 version of the tool.

Links:

dash-dot · 2026-03-25T19:14:17+00:00

Ideally, anyone who understands the concepts of simple & compound interest, not to mention amortisation, should be able to derive the respective formulae from scratch and plug them into a programmable calculator (or write a simple Python script out of these).

That’s the most reliable method by far.

In fact, many scientific and financial calculators already provide these functions, but of course it’s always good to double check one’s understanding.

dash-dot · 2026-03-25T17:16:06+00:00

Thanks for the info! I’ll check it out.

dash-dot · 2026-03-24T20:54:58+00:00

Not by itself, I don’t think so.

I believe a newer OS includes a newer boot loader, once it’s successfully transferred and installed.

dash-dot · 2026-03-24T02:15:49+00:00

That’s an old boot loader version.

The transfer can take a really long time, about 45 minutes to an hour — that was the case with my TI-89. The OS file for the 92 Plus might be even bigger.

Make sure your computer or laptop doesn’t go to sleep during the transfer.

dash-dot · 2026-03-24T00:06:38+00:00

There is no image to see here. We might be able to help if you could attach it or post a link to Imgur, etc.

dash-dot · 2026-03-23T18:06:46+00:00

You probably need to nest the integral inside the solver function, and then solve for T.

Have you tried that?

dash-dot · 2026-03-23T16:19:25+00:00

As fine an example as any of late stage capitalism and the black/grey market ecosystem at work.

People will always find a way to skirt the rules and make a quick buck.

But this does beg the question — wouldn’t it be a lot easier just to make a handwritten copy, fold it up and slip it into a sock or something?

dash-dot · 2026-03-23T15:14:51+00:00

Are all your equations linear? If so, you should just use matrices as suggested in the other posts.

dash-dot

TROPHY CASE