Calculator Community
- Forensic Financial Tests
These are the tests which can give you quite a good profile and accuracy rating for your financial calculator. Any more contributions and confirmation are very much appreciated and I will update the swissmicros page (though I may need to move it off there at some point). ``` | # | Ref | N | I%YR | PV | PMT | FV | P/YR | Mode | |----|------------|--------------|-----------|----------|--------------|-----------|------|-------| | 1 | DM | 38 x 12 | 5.25% | 270'000 | ? | 0 | 12 | end | | 1b | DM | 38 x 12 | ? | 270'000 | -14'584/12 | 0 | 12 | end | | 2 | SlideRule | 360 | 15% → 12% | 100'000 | ?-? | 0 | 12 | end | | 3 | Kahan 1983 | 60x60x24x365 | 10% | 0 | -0.01 | ? | =N | end | | 4 | DM | 480 | 0 → ? | 100'000 | ?→ PMT | 0 | 12 | end | | 5 | Dieter | 10 | ? | 50 | -30 | 400 | 1 | end | | 6 | Dieter | 10 | ? | 50 | -30 | 80 | 1 | end | | 7 | A Chan | 10 | ? | -100 | 10 | 1e-10 | 12 | end | | 8 | Miguel | 32 | ? | -999'999 | 0 | 1e6 | 1 | end | | 9 | DM | ? | 25 | 100000 | -2083.333334 | 0 | 12 | end | | 10 | DM | ? | 25 | 100000 | -2040.816327 | 0 | 12 | begin | | 11 | robve | 60x24x365 | 1/6% → ? | 0 | -0.01 | ?→ FV | =N | end | | 12 | robve | 40 | ? → I%YR | 900 | -400 | -1000 → ? | 1 | begin |
2: https://www.hpmuseum.org/forum/thread-20707.html 3: https://www.hpmuseum.org/forum/thread-1012.html 5, 6: https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv021.cgi?read=234439 7: https://www.hpmuseum.org/forum/thread-18359-post-161549.html#pid161549 8: https://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv017.cgi?read=120592 11, 12: https://www.hpmuseum.org/forum/thread-16565-page-2.html ```
Puzzle 2 is from here, and needs you to calculate PMT given n = 360, I%YR = 15%, PV = 100'000, FV = 0, then calculate PMT, but with I%YR = 12%. Subtract the two results, and put that back into PMT, then change n = 36 and I%YR = 15% again, and calculate PV.
Puzzle 3: you may need to divide I%PY by N depending on how your calculator handles i vs I%YR and what the limit is on P/YR.
Puzzle 4 needs you to calculate PMT first given I%YR = 0, then re-input this back into PMT and calculate I%YR. On the HP-12c this is best done by pressing x<>y twice before putting back into PMT.
Puzzle 11: calculate for FV first, re-input back to FV and compute I%YR.
Puzzle 12: calculate for i first, re-input back into i and compute FV.
The other puzzles are just a solve for '?'.
They can be a bit confusing, so I also did a couple of videos here and here solving them on a DM-42 and HP-12c.
- Sea, beer and a calculator.
A random shot of my calculator 5000 miles from home while I enjoy a beer near the Pacific. We had been discussing how much water was on earth and what size of a ball it would make. I have no affiliation with the brewing company so apologies for the product placement.
- Ooh are we doing Troncet adders? Here's my Addiator
Here's a video from Chris Staecker showing off a similar one: https://youtu.be/2mv45XP48bQ?si=BJmt9rRG-wXdn_jA
- New Casio Graphing Calculator Incoming
I just got an email from Casio Education saying that the next graphing calculator is coming next summer, and that prototypes will be shown off at the National Council of Teachers of Match Expo. I'm in the Chicago area, but tickets for non-members are way outside of my discretionary budget. If anybody is going, you'll have to fill us in!
- Texas Instruments TI-nspire CX CAS
The TI-nspire CX CAS was my first calculator with in integrated CAS, and it was a revelation! I was amazed that a handheld calculator could do symbolic logic, even though the technology goes back to the late '90s. I just never knew that it was a thing. The UI and software for the CX is almost identical to the CX II, though the CX II is more than twice as fast. The touchpad in the middle of the directional button was also improved quite a bit on the CX II. I still use this guy quite a bit, just because it is a special calculator to me. The CAS is not as full-featured as that on either the HP Prime or the Casio fx-CG500, but still powerful as hell. The CX also does not have the third-party support that the TI-89 Titanium has, but is many times faster than it and has the benefit of using a UI that was designed for its form factor.
The pen is an Asvine V200 Titanium M.
- HP-12c Platinum
HP's most accurate financial calculator, oddly enough, and despite only returning the ceiling of solve-for-n.
- Casio BN-20
Sorry the angle is a little funky, but this is one of my two workhorses, the Casio BN-20. This guy gets used almost every day, and is my primary source of truth for my calendar and contacts. It was released in 1998 and has 2 MB of user memory. The spreadsheet function is pretty rudimentary, and the only function that I don't have a lot of experience with. The expense function is the best expense tool I've ever seen on an electronic organizer. I run Xubuntu on modern hardware and can sync the data using Casio PC Sync through Wine and with a USB to serial converter.
- My graduation gift, a TI-82
A gift from my Calculus teacher upon graduation.
Yes manual included. Sadly the 0 (zero) button no longer works, due to battery corrosion... ☹️
- My old TI-36X Solar
This is the calculator that got me through junior high and high school. It even handles fractions, which is what you see on the display there.
355/113 is a very close approximation of PI, accurate to 6 decimal places.
Yes the calculator also has a proper constant for PI, but 355/113 is a pretty nifty trick in it of itself.
355/113 = 3.14159292, at least on this calculator.
- TI-30 (1976)
This example was manufactured on the 7th week of 1979.
https://www.calculator.org/calculators/Texas_Instruments_TI-30.html
- Curta Type I
The Curta mechanical calculators were designed by the Austrian engineer Curt Herzstark, with initial designs from the early 1930s – being half-Jewish, he finished the design while being held prisoner at the Buchenwald concentration camp.
Here's some quotes from the wiki article:
> While I was imprisoned inside Buchenwald I had, after a few days, told the [people] in the work production scheduling department of my ideas. The head of the department, Mr. Munich said, 'See, Herzstark, I understand you've been working on a new thing, a small calculating machine. Do you know, I can give you a tip. We will allow you to make and draw everything. If it is really worth something, then we will give it to the Führer as a present after we win the war. Then, surely, you will be made an Aryan.' For me, that was the first time I thought to myself, my God, if you do this, you can extend your life. And then and there I started to draw the CURTA, the way I had imagined it. > — Curt Herzstark, Oral history interview with Curt Herzstark (1987), pp. 36-37 > > […] > > The Curta's design is a descendant of Gottfried Leibniz's Stepped Reckoner and Charles Thomas's Arithmometer, accumulating values on cogs, which are added or complemented by a stepped drum mechanism. > > Numbers are entered using slides (one slide per digit) on the side of the device. The revolution counter and result counter reside around the shiftable carriage, at the top of the machine. A single turn of the crank adds the input number to the result counter, at any carriage position, and increments the corresponding digit of the revolution counter. Pulling the crank upwards slightly before turning performs a subtraction instead of an addition. Multiplication, division, and other functions require a series of crank and carriage-shifting operations.
- HP 71B Data Type error
My 71B is telling me "Data Error" whenever I try to use the variable "F" - any ideas?
- Ronald Alan Hudson / Calcula · GitLab
Calcula is an RPN calculator with 26 stack levels and 26 storage registers. It is not programmable except you get the Pascal source code and you can create new, possibly complex, functions for the calculator.
https://gitlab.com/waspentalive/calcula
I am looking for suggestions for other functions to add and testing for the existing functions. Free. GPL3 License.
- Found My Old Reliable
This Casio took me through school, and most of uni. Well battle worn, still working. Please dont send me to calculator jail xD.
- Casio fx-CG500
I've had this guy for about a 18 months and it is one of my favorites. It is slower than the HP Prime and the TI-nspire CX II CAS, but still blows the TI-89 Titanium out of the water as far as speed goes. The huge touchscreen gives it a unique UI that is easier to navigate than the TIs. I've found that this is the best of my collection for linear algebra, and it is the easiest of my CAS calculators to use.
- This cutaway demonstration Curta is by far the most expensive collectible I've ever purchased.
You can see the bits moving around inside when you use it.
- Do you think HP will make a great new calculator eventually?
So HP calculators have been ... well not frequent. And from the perspective of a casual calculator user HP might as well not exist. If you wanna buy a new useful scientific calculator it's TI or Casio and maybe sharp. However with the recent announcement that there would be a collectors edition re-release of the HP 15c it looks like the new owners of the HP calculator brand do care! Well at least a bit. So what do you think they will do next? Do you believe HP still has a great calculator in them? What would be your dream HP calculator?
- Why is this in Geometry mode?
Does anybody else find it odd that the HP Prime stashes the vector field plots in the Geometry app instead of the Advanced Graphing app?
- The only thing on my Christmas list when I was 14
My 30+ year-old Casio fx-7700G is the oldest calculator in my collection. It's a little worn, but still works and gets used! It's been a wonderful companion over the years.
- My growing RPN collection
Having used a Ti84+ and Casio FX83GT for my secondary education, and borrowing a HP32 from a classmate at university I really like the stack approach and rpn so I caved with a HP35s which mostly did the job but wasn't pocketable and a bit clumsy for me I found a HP32sii and snapped it up becoming my daily driver for a long time. It scratched an itch i didn't know i had, then wanting to expand my programming and plotting I didnt like the look of the 49g and the 50g being out of my budget I found a nice HP48G that sits on my desk for the more complex work where the RPL hits the needs as well as a "quick" plotter. Even managed to bond with the older grumpy engineers over the calculators and rpn. Im sure my collection will continue to grow.
- Sharp EL-W516T - A Beautiful Disaster
I absolutely love this calculator, with one important caveat: I will never do integrations with this machine except as a test. Its integration algorithm tips over at ridiculously low speeds when it comes to edge cases. I find that it adds to the Sharp's charm, but it definitely affects its usefulness. Aside from that, this nifty little guy has a few features that you can't find on other calculators, and is arguably the best one out there for statistics and tables.
First of all, those buttons labeled D1 through D3 on the top row? Those are this calculator's super power. Programmable Buttons! Let's say that you're in Matrix Mode, and you are doing a whole bunch of stuff with matrices A and B. Typically, to use matrix A it's a three button journey: MATH -> 0 MATRIX -> 0 matA. Instead, you can hit STO D1 and it will let you assign matA to the single button press of D1. Any function from any menu can be mapped to one of those three buttons, saving tons of button presses if you get into the habit of using them.
Most scientifics don't make it too difficult to do base-n calculations, but Sharps make it the easiest out of any manufacturer that I've tried. They are also the only one that supports pental in addition to the standard hex, decimal, octal, and binary. Honestly, I've never had any reason to use pental, but if you're doing something that requires it, this is the only way to go!
It doesn't have any stats features that the Casio fx-991EX or CW don't have, but it does have persistent memory. Anything that you pop into the statistics lists or tables are retained after the calculator is shut down. This is a huge win over the Casios which clear everything when you switch modes or power them off. If you're working with stable sets of data over a longer period of time, this is a lifesaver!
For tables, the Sharp is also a clear winner. When making a table from a function, both the Casios and the TIs have a static value for where x starts. The Casios will only compute 15 steps, while the TIs will continue to calculate as you scroll down through the values. The Sharps not only do rolling calculations going forward, but backwards as well. It's a nice feature to have if you use tables quite often.
Then there's the not so rosy stuff. The aforementioned integrations being the most egregious. It handles easy integrations as well as any other, but when it comes to edge cases it falls down in a light breeze. Take int(e-x, 0, A), for instance. Every non-CAS calculator will crap out as A increases in value, but some are far better than others. The new Casio fx-991CW can handle A all the way up to 2.55x109. Even the Catiga CS-121 can get up to 1500 before it gets inaccurate. The Sharp EL-W516T? 16. It dies at 16. Says that the integral is greater than one. It's embarrassing!
The other place that it distinctly craps out in comparison to other flagship scientific calculators is its SHIFT+SOLVE function. It will only solve algebraic equations with a 0 on one side. It won't solve integrations or derivatives like the Casio, and even the TI 36X Pro can handle equations with x on either side of the equals sign. With the Sharp, you need to perform the algebra to get one side equal to 0 or it errors out.
Overall, it's a great device that gets a lot of use on my desk. You just need to be aware of where it is is weak, and be prepared for those inaccuracies.