# Calculator model with mod function?

I'm wondering does anyone know of a scientific calculator with a mod function?

In C# this is shown as follows (just in case there are any other mods that a mathematical non-savant such as myself wouldn't be aware of)

5 % 4 = 1

I've looked through the most common ones on the web but the function is either not in the list or not present.

I have a little bit of a bias towards Casio calculators as that's what I'm familiar with but will accept any suggestions that can be currently purchased.

Derek

• Do you want exponentiation modulo a number as well? As you tag it cryptography? This is a bit harder than just the modulo operation, as $a^b \pmod{n}$ is not computed by finding $a^b$ first, but by a process that has intermediate reductions, to keep numbers small. Of course, python (as a command line calculator) and similar programs (Pari, etc.) will do this on a computer. – Henno Brandsma Mar 16 '11 at 15:21
• If you use Windows 7 I desire the same functionality as the mod function that calculator offers. I'm afraid I don't know enough to comment on your observation :-( – noonand Mar 16 '11 at 16:24
• Why do you want a calculator model? – Mariano Suárez-Álvarez Mar 16 '11 at 17:40
• Doing a Masters and I need it for exams... – noonand Mar 17 '11 at 22:04
• My calculator has a % key ... but it doesn't do mod, it does percentage. – GEdgar Jul 13 '16 at 15:56

Virtually every graphing calculator made in the recent past has a mod function. Many scientific calculators do as well, though the documentation is often lacking.

• @noonand: Casio classifies the fx-85GT as a "Standard Scientific Calculator" and shows no graphing features in the manual. – Isaac Mar 18 '11 at 14:55
• Apparently the Casio FX 991ES Plus does this I have an email from the Casio distributor in Ireland to this effect. I'm a little bit dubious as the manual makes no reference to a modulo function but I'm also mindful of @Isaac's comment about documentation above. – noonand Mar 28 '11 at 15:47
• @noonand: My concern with the FX 991 ES Plus is that looking at images of it, I can't see where the modulo function would be—I don't see a key labeled for it, nor would it make sense to me for it to be in any of the menus based on the menu names. – Isaac Mar 28 '11 at 17:50
• @noonand: The TI-34 MultiView has a "remainder" function. – Isaac Mar 28 '11 at 17:58
• Just not true, most Casio's don't have a modulo function whatsoever. Of course you can program the functionality in, though. – Benjamin R Oct 25 '15 at 0:59

HP : buy a hewlett packard calculator. the model HP-35S contains hundreds of functions. there is a description here ; http://www.shopping.hp.com/product/calculator/Scientific/1/storefronts/F2215AA%2523ABA;HHOJSID=FW7TNQVJMqHh075qvYbPbRvjvx2K1ybHFyYXGDY9Vr8kpqFlknwg!492383249

The 32Sii used to have a button just for that, on the other hand the HP35s is programmable and you can most probably do it easily.

• While HPs are great and I wouldn't trade my multitude of HPs for any other calculators past or present, the good ones (like the 32s/33s/35s and the 48g/49g/50g series) require learning RPN/postfix notation (though RPN is one of my primary reasons for liking the HPs so much). – Isaac Mar 18 '11 at 2:58
• The 49G and 50G added an "algebraic" mode which uses the usual infix notation. – Nate Eldredge Mar 18 '11 at 3:02
• @Nate: Ah, right. Most people are probably better off with a TI-84 or TI-Nspire than an HP 49G/50G, though. – Isaac Mar 18 '11 at 14:59
• Cannot mark as useful as don't have enough rep; will circle back and do so ASAP ;-) – noonand Mar 28 '11 at 15:49

GeoGebra has a Mod[a,b] command eg

http://web.geogebra.org/?command=Mod[5,4]

If you want to define it to use as a function you can do

mod(x, y) = y (x / y - floor(x / y))

and then use that, eg

http://web.geogebra.org/?command=mod(x,y)=y(x/y-floor(x/y));mod(5,4)

You can calculate mod on any calculator with this algorithm:

Example 27 / 6 = 4.5

27 / 6 = 4.5

4.5 - 4 = 0.5 Get the fractional part

6 * 0.5 = 3 Mul the denominator and fraction

27 mod 6 = 3

Works every time.

• >Works every time.  I'd be worried if it didn't. – 1110101001 Jun 24 '16 at 4:45
• No, it doesn't work every time because of limited precision. If you ask for the fractional part of $\frac {10^{50}+1}{10^{50}}$ you get exactly zero on calculators, so your algorithm will give zero for the mod. – Ross Millikan Jun 24 '16 at 4:55

There is a mod function in TI NSpire and any graphing calculator:

Syntax: mod(number to divide, modulus (divisor))

E.g. mod(35^51, 319) Enter yields 167

The TI-36x pro has a mod button under the Math menu.

• When responding to a 7+ year old Question with Accepted and upvoted Answers, one should highlight the new information provided relative to earlier responses. Giving the shortest of all Answers is not of benefit in this situation. – hardmath Jul 6 '18 at 2:56
• @hardmath There is no time limit to the answers in the SE. I think the problem is not with the answer, but with the question (might be ontopic on hardwarerecs.stackexchange.com). – peterh says reinstate Monica Jul 6 '18 at 4:07
• @peterh: It isn't a matter of a "time limit to the answers", but rather about taking the time to write a good Answer that reflects some improvement on posts from years gone by. New users should be encouraged to write material that contributes to the goals of Math.SE, and the temptation to write spuriously brief responses deterred. – hardmath Jul 6 '18 at 4:11
• @hardmath It is all right - except that questions can be answered any time. – peterh says reinstate Monica Jul 6 '18 at 4:22
• Google doesn't really care how old a question is. It's always going to come up. The truth is there aren't a lot of good answers in this thread. I have almost every calculator listed, and if someone wants an easy mod button, the TI-36x pro is the best calculator "now" listed in this thread. I'm an avid user of the the HP35s, but it's remainder display is a pain for this. Get the TI-36x if you are reading this to decide what calculator to buy. – Brady Nelson Jul 6 '18 at 15:34

## protected by hardmathJul 6 '18 at 2:56

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