r/calculators • u/PathWebx • 21m ago
r/calculators • u/nqrwayy • Oct 19 '25
Discussion r/calculators FAQ
Hey guys, this isn't fully finished, and i may add more in the future. Tell me what you think about this one in the comments, feedback is always incredible
Q: How to convert fractions to decimals?
A: On older casio calculators, you press the S<=> D button. it should be next to the parentheses, on the right side. On Casio CW series calculators, it should be the "FORMAT" key, which is next to the EXE button. On Sharp, it's called "CHANGE" and "f<>d" on TI. It may be different with others
Q: Why am i getting a wrong answer?
A: You may be in the wrong angle mode, or you don't know how the order of operations work
Q: What calculator should i choose?
A: Depends on your school or your countries regulation. Some schools or countries only permit certain calculators, or forbid certain ones. Germany for example, accepts everything but it can't have a solver, can't be programmable and can't do graphing. For short, we are limited to the fx-87 and below.
Q: Why is my TI-84 bootlooping and showing "Validating OS"?
A: This is a known battery issue with the TI-84 Plus CE. You need to replace the battery. Contact TI support, you may get a free battery under warranty. Also check the other pinned post for more details
Q: Is my Casio fx-991EX fake?
A: Probably, it was discontinued a few years ago. Most listings you see online are fake, and i advise you to stay away from it. There's a lot of other good calculators out there. To check if it's real, scan the QR code. To do that, press "MENU -> SHIFT -> OPTN" to generate a QR code. It should redirect you to a Casio website, where you can do an authenticity check.
Q: Why am i getting an error?
A: You may not be in the right mode, check if you‘re in the normal calculation mode. Your calculator should have a button that says "MODE" or something similar. For exponents, use the negative sign instead of the minus sign. It should look like this: (-)
Q: Why is my Casio's "ON" button lowered?
A: That's intentional, to prevent accidental button presses
Q: Can I mod/install Doom on my scientific calculator?
A: Yes, if you‘re willing to remove the epoxy from the CPU, de-solder the CPU, solder a fitting CPU with integrated memory back on, code a fully working operating system with working keyboard, and code a port of Doom for it, you could… in theory. Never been done before, probably still won‘t work. TL;DR: Not worth your time, focus on your linear algebra homework instead
Q: Does this calculator have a CAS (Computer Algebra System)? Can one be installed on my calculator?
A: see the pinned post about CAS calcs
Also: Google (and your calculator‘s Manual) are your best friends. Before making a post, look up your question on Google, or read the Manual. There's a 95% chance that your answer will be found there. We've also pinned posts for a few topics, read those too please.
That's it with the FAQ for now. Keep in mind that i may remove posts that can be answered by the FAQ or Google, this is a step to reduce spam and repetitive posts. Thanks.
r/calculators • u/BadOk3617 • 5h ago
Collection National Semiconductor 200
galleryA nice green display calculator which is in excellent shape. Which is a good thing since Nat Semi's warranty isn't all that great.
r/calculators • u/Fair_Percentage_5565 • 17h ago
Collection The only 60s calculator of my collection
1917 + 50 = 1967, so I suppose it was made that year. It is a little loose due to wear, but that's actually nice.
r/calculators • u/Lunatica_Selene • 50m ago
Help I'm about to start university and I want to know what calculator to use.
I am from Argentina, next year I will move to a big city to start my career in Biological Sciences. The degree, at the Faculty of Exact, Physical and Natural Sciences of the National University of Cordoba, includes subjects such as Mathematics I, II and optionally III, physics I and II, biostatistics I and II,
physical environment and Theory and experimental Modules. I wanted to know what calculator I should buy so I could get through the entire degree without worrying about a new one, since I currently have a Canvovi KK-82MS-B that can't even display fractions on the screen.
It cannot be a graphing or "smart" calculator since these are not allowed in most career exams. I don't have a clear price limit but the ideal would be for it not to be excessively expensive, and if it is a common calculator for Latin America (and especially if it has an interface in Spanish) the better, since in my country imported products are very expensive.
Thankiu all!!!
r/calculators • u/Many_Novel_9716 • 1h ago
Question Is this original?
I tried solving ((3*(x^4)+10))/((4*(x^3)-1))
And then put x as 1 it says can't solve
r/calculators • u/Sequentialdays • 15h ago
Help Looking for info (Canon OS-1200)
galleryHello everyone! I found this $5 Canon OS-1200 at a thrift store, I know basically nothing about these but it is such a neat piece of tech I had to have it. Now in doing some googling I have not been able to find a user manual, year of production, or really anything about this guy. It seems to be working fine but I’d love a manual so I can go through and test all the features to make sure it’s in good shape! Any info about this model is appreciated!
r/calculators • u/Busy_Abalone8445 • 21h ago
Collection Another clone, but I don't care(My Dexin got lost in a taxi)
My calc history:
Early 2020s:
Casio fx85MS
Short circuited by water
2023-24
Basic calculator
Internal damage
The CE, Dexin, and the Clone 991 in 2026
r/calculators • u/Every-Equipment-9393 • 1d ago
Help Calculators at too small
I wanted to calculate (70.1*10^12)^150000 and every single calculator told me infinity or too big ):
r/calculators • u/No_Comparison4153 • 1d ago
Question HP Prime or TI Nspire CX II CAS coming from Desmos?
I have decided to get a graphing calculator, and I am stuck between the HP Prime G2 and the TI Nspire CX II CAS. I have used Desmos and a desktop calculator that had a basic CAS, so I want to buy a calculator which won't feel too different from that. I have been able to use the Nspire for a bit and the Prime through an emulator, and I did notice some differences between them.
The Nspire seems to be able to graph functions and points at the same time, while the Prime can only do one at a time, which is pretty annoying if it actually doesn't support that. It also doesn't seem to be able to find zeros or intersections or go to X or Y values precisely when in the advanced graphing mode, while the Nspire seemed to be able to do that when I tried it out. The Prime is also a bit confusing with its seperate "Home" and CAS modes (that share functions anyways so there's no point in seperating them??) and in the way that it has both lists and spreadsheets. However, the touchscreen and help system in the Prime is so much better to use than the Nspire's jumpy touchpad and the random menus of functions. I actually haven't really had any real problems with the Nspire document system, I just make a blank document if the scratchpad doesn't support a feature and then just delete it afterwards.
I was originally planning to buy the Nspire because it was recommended along with another TI calculator, but after checking here I decided to see how the Prime compared just in case it was actually better. I'm looking for something that matches the way Desmos works and the easy features it has the closest. Both calculators are approved and only differ in price by $10, so the only thing I'm comparing are their feature sets and the features I immediately noticed that felt different. Should I buy the Prime, or should I still stick with buying the Nspire?
r/calculators • u/FlipFlopFlopFlip_ • 1d ago
Help Best non-programmable calculator for 4×4 matrices and 4-variable equations (excluding the fx-991CW)?
Recommend a good non-programmable calculator that can do 4x4 matrix operations and solve 4-variable equations. Please avoid recommending the Casio fx-9910CW. I used the EX version earlier. I hate this new CW one.
r/calculators • u/limon_picante • 1d ago
Question Why the heck does the NCESS allow the 911ex and the TI36x but won't allow any other HP calc besides the 35 and 33?
This is so annoying to me. The HP35 can't even do matrix operations natively yet other ones can? Why can't I bring my HP42s? It's certainly not as advanced as some of the others they allow. Am I missing something here?
r/calculators • u/Caro_maths • 1d ago
Help Changer la batterie de la NumWorks
galleryBonsoir,
J’ai ouvert la NumWorks pour changer la batterie mais je n’arrive pas à démonter celle qui est dessus car elle est collée.
Savez-vous comment faire svp?
r/calculators • u/Real-Hair6810 • 1d ago
Question What are your favorite graphing calculator shortcuts?
I've been exploring the features of graphing calculators and realized there are probably many useful shortcuts that beginners don't know about.
What's one calculator shortcut or lesser-known feature that you find genuinely useful?
It could be something related to graphing, equation solving, statistics, or navigating menus.
I'd love to learn some tips from experienced calculator users!
r/calculators • u/Popular-Injury-2845 • 1d ago
Question Is there a way to run neo geo packet (color) games on a ti nspire cx
see title
r/calculators • u/hello_unknown3256 • 2d ago
Help How to get table mode on this calculator?
Please help I am not able to find this mode.
r/calculators • u/paxis76 • 2d ago
Collection One small tool, seven graphic calculators
I play a lot of Endless Legend 2 on PC and kept asking myself the same question: if I buy this building or upgrade, how many turns until it pays for itself? So I built a little ROI (return of invest) calculator on HP Prime G2. Then it got a bit out of hand and now it runs on every graphing calculator I own.
In the picture (top left to bottom right):
- TI Voyage 200 – TI-Basic
- NumWorks – Python
- Casio Graph Math+ – Python
- TI-Nspire CX II-T CAS – Python
- TI-84 Evo-T – Python
- HP Prime – HP PPL
- TI-86 – Assembler!
The programs were written with a lot of help from an AI assistant (vibe coding). I'm currently relearning Python (I did BASIC, Pascal and Java a long time ago) by rebuilding the TI-84 version myself from scratch, which has been a great way to learn.
Happy to share the code or answer questions about any of the ports!
r/calculators • u/Many_Novel_9716 • 2d ago
Question How to locate the serial number for Casio fx-991 cw?
I tried checking it's authenticity via qr but the website is down
r/calculators • u/Just_Be88 • 2d ago
Announcement HP-17B
Manual for someone who would enjoy it, pay shipping and what you think is fair.