Calculator FAQs

We've compiled a list of common questions and concerns relating to Casio calculators.

If you can't find what you're looking for, don't hesitate to contact our customer service team for further assistance.

General Use

Basic Calculations - Office

1. How to set "Tax Rate"

(1) If "Rate set" is printed above [%] key with your calculator,

  1. Press [AC] and hold [%] for about two seconds.
  2. Input Tax Rate and then [%].

* You can check Tax rate by pressing [AC] and then inputting [TAX+]

(2) If "Set" is printed above [%] key with your

  1. Press [AC] and hold [%] for about two seconds.
  2. Input [TAX+].
  3. Input Tax Rate and then [%].

* You can check Tax rate by pressing [AC] and then inputting [TAX+]

2. How to calculate Price-plus-Tax and Price-less-Tax.

(1) How much is Price-plus-Tax of 100? 

  • Press [AC], and input 100 [TAX+].

(2) How much is the Price-less-Tax of 105?

  • Press [AC], and input 105 [TAX-].

3. Tax Rate Setting Precaution

Replacing the battery or blocking the calculator from sunlight while battery

power is low may cause your tax rate setting or memory contents to be changed or lost. Replace the battery as soon as possible when it becomes weak and correct the tax rate setting, if necessary.

Always be sure to check the tax rate setting before starting tax calculation.

F: Floating Decimal

CUT: Values are cut off to the number of decimal places specified by the current Decimal Place Selector setting

UP: Values are rounded up to the number of decimal places
specified by the current Decimal Place Selector setting

5/4: Values are rounded off (0,1,2,3,4 are cut off; 5,6,7,8,9 are rounded up) to the number of decimal places specified by the current Decimal Place Selector setting

4,3,2,1,0: Specifies the number of decimal places as 4,3,2,1,0

 ADD2: 2 decimal places are assumed for entries and results
of all addition and subtraction operations. Entering 2 only results in a value of 0.02 for the entry. If you use the ""."" key during entry of a value, the decimal point is included at the place you specify. This mode
is no effect on multiplication and division operations.

Make sure that you are following the correct procedure.

Adding 10%: 200 [×] 10 [%] [+]

Subtract 10%: 200 [×] 10 [%] [-]

The [MU] key is used for markup. Here is an example of the
markup function. If the purchase price of an item is $120 and the profit rate is 25%, what would the selling price and profit be?

 Enter the following:

120 [MU] 25 [%] (result 160)

[=] (result 40)

The selling price would be $160, and the profit would be

To clarify further, the profit rate is relative to the selling price, meaning the percentage of the selling price that is profit. In the example above, the selling price (as computed by the calculator) is $160, so the profit rate of 25% gives a profit of $40.

Before performing the calculation, we did not know what the selling price would be, just that the purchase price of $120 should be 75% of that unknown amount (as 100% - 25% = 75%).

To look at it another way, we are asking the calculator to tell us the number that $120 is 75% of. $160 is that number, and then 25% of that (the profit) is $40.

Whenever the “=” Key has been pressed, the result will be stored into the Grand Total Memory!

The “GT” Key is to recall the Grand Total Memory!

Its function is similar to the “MR” Key, both of them are used for recalling
the Memory Content!

Please note that the GT Memory will be cleared by pressing the “AC” Key in most of the CASIO Models! For other Models, it can only be cleared by pressing the “GT” Key twice!

1. Press [M/EX] to toggle between the Conversion
mode and Memory mode.
2. The “EXCH” indicator on the display indicates the Conversion mode.

  • To set conversion rates
    Currency 1 [C1] is your home country currency, and so it is always set to 1.
    Currency 2 [C2] and Currency 3 [C3] are for the currencies of two other countries, and you can change these rates as required.
    Some models have one more conversion rate setting named Currency 4 [C4], whose
    rate can also be changed.

To set a conversion rate 1 USD ([C1] home currency) = 0.95 EUR for Currency 2
Press [AC], and hold [%] about two seconds. Then input [C2] 0.95 [%].
Using [C1] and [C2] above, convert 95 EUR to USD.
Press [AC], Then input 95 [C2] [C1].
Using [C1] and [C2] above, convert 100 USD to EUR.
Press [AC], and input 100 [C1] [C2].

*You can check the currently set rate by pressing [AC] and then [C2]
*Some models are equipped with [C/AC] key instead of separate [C] and [AC] keys. For such models, press [C/AC] once to perform [C] operation or twice to perform [AC] operation.

How to change the currency rate:
When you press the [M/EX] key, it toggles between conversion mode and memory mode.

You will see "EXCH" on the display when in conversion mode. C1, C2,
and C3 are three conversion rates. C1 is your home country currency, and so it is always set to 1. C2 and C3 are rates for two other countries, which you can change. For example, if you want to set a conversion rate of $1 to 0.95 euros, here is what you would do (using C1 for US dollars and C2 for euros):

  • Press [AC]
  • Hold [SET/%] for about two seconds until "SET" appears
  • Press [C2] to select currency 2
  • Input the conversion rate (0.95) and then press [SET/%] to store it in memory
  • You can check the currently set rate at any time by pressing [AC] and then [C2].

"+", "-", "×", "÷" twice to register
a constant. The "K" indicator is displayed to indicate that Constant Calculation is in effect.

This will reverse the order of the input values, for example, if you input
4--3, the result of the constant calculation will be 3-4!

Round Numbers Calculation occurs on an overflow error. For example (8 digits calculation): 99’999’999 x 123 = E 122.99999 (the round number of the result is the display value x 100’000’000 = 12’299’999’000,
where the actual answer is 12’299’999’877). Then press [C] to clear the error and continue the calculation.

When used in calculation, [◇/#] is used as a subtotal key. The printout symbol will be (◇). When used in printing reference number, date and
etc that not related in calculation, The printout symbol will be (#).

For the number of addition and subtraction, press [◇/#] or [*] will print out the result with the total item count.

For the number of [*] key operation, press [G*]. For some printers, pressing [M◇] or [M*] key will print the total number of [M+] and [M-] key operations up to that point along with the value stored in the independent memory. Besides, of course, pressing [IT] key can recall the item no.

The HR-8 series have a [DEC] key with F, 0, 2, and 5/4 over it, while many other calculators models have a switch labeled [F CUT 5/4].

The button or switch can control rounding off to a certain number of decimal places. F is floating point (no F indicator on screen), 0 rounds off to 0 places after decimal point, and 2 rounds off to 2 places after decimal point.

The 5/4 applies to either the 0 or 2 modes, and describes the type of rounding off that is performed. The calculator will round down if the digit after the one you are rounding to is 4 or lower, and round up if the digit is 5 or higher.

ADD Mode Calculation will add 2 decimal places even not pressing [.] key when the Mode Selector is not at "F".

For addition and subtraction, both ADD2+ and ADD2x mode will add 2 decimal places with the inputted number. (e.g. input 2324 + will turn to 23.24)

For multiplication and division, only ADD2x mode can add 2 decimal places. (e.g. input 3 750 = will turn to 3 7.50 = 22.50 in result)

For both ITEM+ and ITEM +/- mode, the total number of addition and subtraction items is printed with the result when [◇/#] or [*] is pressed.

But the item count method is
different. Under ITEM +/- mode, addition will be counted as "+1"
whereas subtraction will be counted as "-1". However, under the ITEM+
mode, both addition and subtraction will be counted as "+1".

No, a regular percentage or ratio calculation result is automatically stored in the total memory used for accumulation of totals.

But for the add-on and discount, their results will not be put in the
total memory. (e.g. press 5 x 10 % + *, the total memory will be 0)

That depends on whether the printer has back-up batteries or not. Normally the printer with back-up batteries can retain the value stored in memory when the calculator is not plugged in to an AC power outlet.

Use the keys [×][=].

For example, to get 2.5 square, you can press 2.5 [×] [×] [=].

To get power 3 of 2.5, press 2.5 [×] [×] [=] [=].

To get power 4 of 2.5, press 2.5 [×] [×] [=] [=] [=].


“E” (icon will be ON under the following situations:

  1. Overflow Error (Please refer the "Overflow error FAQ")
  2. Memory Overflow Error(both Independent Memory and GT Memory)
  3. Any number divided by zero
  4. Square Root on any Negative Number

In order to clear the "E" symbol, you can either press the C Key or simply press the AC Key to clear the whole operation.

Whenever the integer part of a calculation result is longer than the max. number of digits which this calculator can hold, the result would be an Overflow Error! The result will be presented in Round Number

(Please refer to Round Number Calculation FAQ)

First, check the batteries, and ensure there is not a paper jam in the printer.

If both are fine, then while the calculator is in the "Print" mode,
press the [CA] (or [AC]) button 20 times consecutively to clear out memory buffers.

Try some numerical calculations, and if the problem persists, repeat pressing the [CA] button 20 times.

If the problem still persists, then the calculator may require service.

This is not calculation error, please check the batteries/suitable voltage or whether there is any paper jam with the printer.


Slide off the upper cover of the calculator, and cut across the paper roll to form a clean end.

If you are mounting the roll externally (outside of the back of the calculator), then look for a slot in the rear of the calculator, which will
accept the paper. Feed the end of the paper through the rear slot, and then into the internal feed slot, and hold the [FEED] key.

After that, you can flip the arm back to mount the roll and replace the upper cover.

If you want to place the roll inside of the calculator, then you need to feed
from the bottom of the roll into the internal feed slot, and hold the [FEED] key. After you are finished, replace the upper cover.

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