# Calculate remainder on Casio fx-991 ES Calculator

Is it possible or not to calculate remainder through use of Casio fx-991 ES Calculator. If possible then how

for example :- I have to calculate remainder of 2345763534 rem 24 and other media except calculator is forbidden. If this isn't possible through calculator then any short cut method are also appreciated.

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Divide 2345763534 by 24. Take the integer part of the quotient. Multiply by 24, and subtract that product from the original 2345763534. This difference is your remainder. – oldrinb Apr 1 '13 at 2:38
@oldrinb: we had the same idea. – Thomas Apr 1 '13 at 2:40
@Thomas I hope :-) – oldrinb Apr 1 '13 at 2:43
@oldrinb: Since your comment was a bit faster than my answer, you should add an answer :) – Thomas Apr 1 '13 at 2:44
I don't know about my first question i.e whether it is possible in calculator directly or not... – nKandel Apr 1 '13 at 10:48

Use the calculator to find $$2345763534/ 24 = 97740147.25$$ That is the remainder is $$2345763534 - 24\cdot 97740147 = \dots$$

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Or easier: $2345763534/24=97740147.25$ so the remainder is $24\cdot0.25$. This requires the same amount of steps, but can be done without remembering or writing down old answers! – Dominique Apr 30 '15 at 6:41
@Nick: Good point. I tend to do it the other way because when programming one often has a floor function. – Thomas Apr 30 '15 at 15:10

I thought that I'd add the answer I found here as I found it more helpful than the current answer.

I am afraid that this calculator don't have any modulo function. However there is quite simple way how to count modulo using display mode ab/c (instead of traditional d/c).

How to switch display mode to ab/c:

• go to settings (Shift + mode)
• press arrow down (to view more settings)
• select "ab/c" (number 1).

Then do your calculation (in comp mode), like 50 / 3 and you will see 16 2/3 thus mod is 2 or try 54 / 7 which is 7 5/7 (mod is 5). If you don't see any fraction then mod is 0 like 50 / 5 is 10.

The remainder fraction is shown in reduced form, so 60 / 8 will result in 7 1/2. Remainder is 1/2 which is 4/8 and mod is 4.

EDIT: Note that this doesn't work for everything. Especially if the fraction can be simplified (e.g. 6 mod 4). But I still believe it's a useful shortcut to keep in mind, just make sure the fraction has the modulus as the denominator.

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this doesn't work if d number is too large i.e on range of 10+ digit... anyway thanks for the answer – nKandel Jun 1 '13 at 15:19

I know this is an old post, but you could do this on any calculator

5 % 4 = ? (5 mod 4)

5/4 = 1.25 to get the decimal form of the remainder subtract the number on left of decimal from result of 5/4

1.25 - 1 = .25 <-- the remainder .25 * 4 = 1 <-- remainder converted from decimal form

so...

5 mod 4 = 1

61 % 9 = ?

61/9 = 6.7777777777777777777777777777778

6.7777777777777777777777777777778 - 6

= 0.7777777777777777777777777777778

9 * 0.7777777777777777777777777777778 = 7

so 61 % 9 = 7

With this method, there might be cases where the multiplication at the end results in another decimal but this is due to rounding so just round up or down to the nearest whole number and that's your remainder

ie: on a cheap calculator with not so many decimal places

61 % 9 = ?

61/9 = 6.78

6.78 - 6 = 0.78

9 * 0.78 = 7.02

round 7.02 to whole # = 7

61 % 9 = 7

12 % 3 = ? 12/3 = 4.00 4.00 - 4 = 0 0 * 3 = 0 12 % 3 = 0

Note: This method doesn't work for negative integers

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what if the starting number is so great that it doesn't fit the display of the calculator? – mau Oct 9 '13 at 12:21
This is a manual method means you need to first divide then subtract and again multiply. This isn't method I would expecting at time of posting this question... Anyway thanks for answer. – nKandel Oct 17 '13 at 5:40

I think jdeo's method works for negative integers aswell: -7 mod 4

-7/4=-1.75

Next step is make a positive fraction that is less than 1 -1.75+2=0.25

Then 0.25*4=1

Therefore -7 mod 4 = 1

Please do let me know if this is wrong :) Thanks

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Suppose you want to know what A mod B is, you can do the following then:

Pol(-Rec(1/(2π) , 2π×A/B), Y)(π - Y)B

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Another way of doing this is with the BASE-N mode. In this mode, the divisions are made as integer calculations in a programming language A/B, so the A%B (A mod B) operation can be obtained as:

A−B(A÷B)

• Pros: This works on any basis (including 10) and for negative numbers.
• Cons: Since the CALC mode is not allowed into the BASE-N mode, A and B values should be previously STOred.
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