Among its many features, the Casio FX-115ES can perform equation calculations. In order to do so, you must set the calculator into an equation mode called “EQN Mode.” You then can specify equation types, such as quadratic equations, and can input coefficients using the coefficient editor screen. The calculator then will display the solutions. Performing equation calculations with the FX-115ES is accomplished with the proper programming.

Change the calculator to “EQN Mode” by pressing “Mode” and then “5”. Press the “1” key to choose simultaneous linear equations with two unknowns, Press “2” to select simultaneous linear equations with three unknowns. Press “3” to choose quadratic equations and press “4” for cubic equations.

Input coefficients using the coefficient editor screen. Data you enter with the keyboard appears in the cell where the cursor is. The cursor moves to the right so that you can program the next piece of data.

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Press the “Equals” button to register the value and display up to six digits of the cell. Change a cell by moving the cursor to it and inputting new data. Press “AC” to clear current input.

Press “Equals” when you have programmed all of the equation data, and the solution is displayed. Further pressing of “Equals” provides more solutions if there are any, and the final press of “Equals” takes you back to the coefficient editor screen where you can change your programmed equations if desired.