Instructions for a Casio FX

By Michelle Enos

Updated September 26, 2017

Casio manufactures calculators for business, finance and school use.
i calculator image by Szymon Apanowicz from

Casio is a Japanese manufacturer of electronics such as clocks, musical instruments, cameras and calculators such as the FX-260. The FX is a scientific calculator, which means that on top of the basic addition and subtraction features of a simple calculator, it can also perform more complex mathematical functions to solve algebraic equations. It does not have graphing capabilities.

Learn how to use your Casio calculator's basic functions. The "On" button turns power on and "C" clears the displayed value. Many keys are marked with two functions; press "shift" to use the functions marked above each key. Press "AC" to begin a new calculation. Find the keys for basic calculation; addition is a "+" and subtraction is a "-." Parentheses are available as well, although the calculator uses "order of operations," meaning if you input five plus four times six, the FX will calculate four times six and then add five.

Perform "constant calculations" by inputting a number and then pressing "+," "-," "x" or "÷" twice to make the number a constant. Every time you press the "=," that constant will be added (or subtracted, multiplied or divided) to the number on the display. For example, if you type in three plus four equals, the display will show the answer as 7. If you press "=" again, the calculator will add four to seven and display 11. To clear a constant, press "AC."

The Casio FX can also be used to add, subtract, multiply and divide fractions. Use the "a b/c" key to input fractions. The "a" key refers to the mixed number part of the fraction, "b" is the numerator (top number) and "c" is the denominator (bottom number).

To input three-quarters, press three, then "a b/c," then four. To input two and three-fourths, press two, "a b/c," three, "a b/c," and four.

Answers to fraction calculations will always be displayed in decimal form. Use the "a b/c" to convert the displayed decimal to a fraction.

Use the multiplication function to find the percentage of a number; to calculate percentage of one number to another, use division.

For example: To find 15 percent of 100, enter "100 x 15%." To find what percentage of 100 is 15, enter "100 ÷ 15%."

Perform square root and power calculations with your Casio FX. The "X" with a superscript two squares a number, while "X" with a superscript three cubes a number. "X" with a superscript "Y" raises the number to another power. For example, to enter three to the power of five, enter three, then the X superscript Y key, then five.

The FX also has a square root key and a cube root key (the cube root key looks like the square root key with a little three in front of it). The key with an X and "1/y" in the superscript calculates another root of a number. For example, to find the fourth root of 100, enter 100, the previously mentioned key and then four.


Not all functions of the Casio FX are listed in this article. For more, check out the manual listed in the resources section of this page.