Online or Phone app Calculator that works with SI prefixes

[mkeveney]

Ages ago I had a pocket calculator with a mode that would accept input and display results using SI prefixes.

i.e. pressing buttons:

3 k * 1 0 µ =

Would display the result as:

30m

Does anyone know of an online equivalent? or phone app maybe? I've been looking all over.

-Matt

[barshatriplee]

Cannot find any online converter/app like this. There are many apps that will convert one unit to another. But they do not have the option to multiply two different units.

[bingo600]

On linux i use Qualculate - Is in ie. the ubuntu repos (older vers)
https://qalculate.github.io/

[bingo600]

Btw: It is whining (ignoring the µ)  - mesg : Trailing µ not valid (ignored)  ... You have absolutely no units

If you use µm  - It gives 30 mm

[AndyC_772]

Casio fx-991ms - I use that feature all the time, though it does seem quite rare, if indeed any calculators are still made with that feature at all.

If you find a phone calc app that does the same, I'd love to hear about it too.

[BeBuLamar]

There is another way to do it without a specific calculator is to use scientific notation and remember the prefix values for the exponent. For example k=3, m=-3, M=6 etc...
I have the HP 48 caculators which can do calculation with units and with prefix but you have to enter the unit with and the prefix which is quite slow. It's available as free apps for both Windows and phone app.

[Infraviolet]

On a Linux PC the Speedcrunch program is a GUI calculator which will let you type in things like "5kilo" or "3micro", it won't work for just the single letter prefixes though. It also happily accepts "5e3" or "3e-6". There might be Windows or Mac versions of Speedcrunch available.

[rstofer]

How about PhySyCalc

https://www.physyapps.com/

$5 and runs on my iPad.  I don't have an iPhone and I couldn't find the app on the Google site.

[mkeveney]

Thanks all for your replies.

For reference, The calculator I had was the middle one in the first frame of this video:
   

Except I think mine was the Casio-branded version.  Anyone know the model number?  I've been looking online & can't seem to spot it anywhere.

Really though, I'd rather have a laptop or phone app, since I'll always have one of those handy.  A separate device is just going to get lost again.

> AndyC_772
That Casio looks pretty close, but I wonder how long it would take me to get used to the VPAM entry.

> bingo600
Entering the units would be a pain. I know what units I'm using, I just want the prefixes to be automatic so I don't miss a zero when entering or reading the values.

> rstofer
Same point.  Does PhySyCalc let you enter _just_ the prefixes?  Or do you have to enter the _units_ as well?

> BeBuLamar
That's kind-of what I do now.  I use LibreOffice calc as an ad-hoc calculator, but that doesn't help with _entering_ the values, and it's all too cumbersome for a quick calculation.

In fact, even the original calculator took longer than I'd like.  As I recall, you first had to put it into "engineering mode" somehow; then to enter a prefix you had to use a shift button.

My dream app would have dedicated buttons for the prefixes if it was a phone app.  If it was a web app, it could just recognize m,u,n,p,f,k,M,G,T,P when typed as a number suffix.

[mkeveney]

Found it.
It appears to be the Casio fx-115D Super-FX
https://ithistory.org/db/hardware/casio-computer-co-ltd/casio-fx-115d-super-fx

[Gyro]

It very quickly becomes easier (and less button intensive) to simply put the calculator in Engineering mode (rather than scientific) so that the display is in 10³ increments and memorise what u,m,k,M etc. stand for.

[mqsaharan]

For a phone or tablet calculator app (android) I use the HiPER Calc https://play.google.com/store/apps/details?id=cz.hipercalc&hl=en&gl=US
It accepts engineering symbols and these can be selected with shift EXP button. It shows the list and you can select the desired symbol. I mainly use it as an RPN calculator.

[rstofer]

> rstofer
Same point.  Does PhySyCalc let you enter _just_ the prefixes?  Or do you have to enter the _units_ as well?

I have just started to play with it, I know nothing.  You do not have to carry the units if you don't want units in the result.

The only thing I can't find is a way to get the result back in scientific notation.  The calculator prefers full decimal numbers so 1E9 comes out as 1000000000 which isn't nearly as intuitive.  With units included, I think this issue disappears.

There are about a batrillion defined units - whatever you need, it's in there somewhere.

[mkeveney]

> It very quickly becomes easier (and less button intensive) to simply put the calculator in Engineering mode (rather than scientific) so that the display is in 103 increments and memorise what u,m,k,M etc. stand for.

That's what I'm doing now.  Maybe our calculators are different.

On my _present_ calculator, to enter the equivalent of 20µ, I have to click 5 keys: 2 0 Exp 6 +/- ... which displays 20. -006

How does your calculator work?

[reybae]

I just verified that it works on my Casio fx-991ex calculator the way you described, albeit with some usage of menus a video of it in use. I have an iOS app on my phone called NCalc that mimics the Casio fx-991ex the app.

As for android apps, I'm not sure what you could use. Good luck.

[BeBuLamar]

Going into menu is pretty slow, I much rather use the engineering notation.

[tooki]

Since it exists as both a desktop app (free) and mobile app ($), I’ll add that the HP Prime calculator and its emulators can do it, kinda sorta.

If you enter it exactly like this, for example:
\$\text{USIMPLIFY}\left( \frac{\text{3_(V)}}{\text{250_(Ohm)}} \right)\$

…the result is (in engineering notation, as I have it set):

12.000E-3_A

It does accept prefixes on the input:
\$\text{USIMPLIFY}\left( \frac{\text{3.2_(V)}}{\text{5_(mA)}} \right) \$ = 640.000E0_Ohm

But if you want a prefix on the output, you have to expressly perform a conversion:

\$\text{CONVERT}\left( \text{USIMPLIFY}\left( \frac{\text{3_(V)}}{\text{250_(Ohm)}} \right), \text{1_(mA)} \right) \$ = 12.000E0_mA

Using CONVERT, you can leave out the USIMPLIFY command entirely, the result is the same, and it will return an error if you ask for a conversion incompatible with the units in the calculation.

\$\text{CONVERT}\left( \frac{\text{3_(V)}}{\text{250_(Ohm)}}, \text{1_(mA)} \right) \$ = 12.000E0_mA

\$\text{CONVERT}\left( \frac{\text{3_(V)}}{\text{250_(mA)}}, \text{1_(mA)} \right) \$ = Error: Inconsistent units

But of course, this means you must know in advance what output unit (and prefix) you want. (Note that the “1” in the “1_(mA)” term is completely arbitrary and can be any number, without affecting the output. It’s nothing more than a placeholder for the unit to attach to.)

You might be wondering what the USIMPLIFY (“unit simplify”) command does. Well, without it, the output units are left intact:

\$\frac{\text{3_(V)}}{\text{250_(Ohm)}} \$ = 12.000E-3_\$\frac{\text{V}}{\text{Ohm}} \$

[BeBuLamar]

I tried the HP Prime but gave up on using units. Way too complicated.

[Gyro]

> It very quickly becomes easier (and less button intensive) to simply put the calculator in Engineering mode (rather than scientific) so that the display is in 103 increments and memorise what u,m,k,M etc. stand for.

That's what I'm doing now.  Maybe our calculators are different.

On my _present_ calculator, to enter the equivalent of 20µ, I have to click 5 keys: 2 0 Exp 6 +/- ... which displays 20. -006

How does your calculator work?

The same (although my display reads 20. E-6 rather than redundant exponent zeros). I just find it easier to use the same , well memorized numeric key positions than looking for the appropriate symbol key. Personal preference in avoiding clutter I guess. As long as the display is working in engineering mode (powers of 3) then I find it intuitive.

[wasedadoc]

HP49 or 50 physical calculators.  There are emulators for Windows and Android.