CALCULATE
Below are some examples of the Natural Textbook Display™ input/output notation, as found by selecting the Calculate

icon from the Main Menu of the fx-991EX.
From the Main Menu, use the arrow keys tohighlight the Calculate icon, then press =or press 1.

Fractions and mixed numbers can be entered using
a and qaA, respectively.
To enter the calculation to the left, press
a7$8$+qaA2$3$
11p.
To change the solution to a decimal format,
press n.

Press qnN to convert the result intoa mixed-number format.

When inputting radical expressions, the radical bar
automatically extends as additional characters are typed.
Press s24=.

The output will be displayed in simplest radical form, but canbe converted into a decimal approximation by pressing n.

fx-991EX Quick Start Guide

3

CALCULATEClassWiz is capable of recognizing and combining like radicals.
Press s24$+s150=.

It can also calculate unlike radicals. Presss24$-s98=.

Higher-order radicals can be beautifully expressed using
Natural Textbook Display™ input.
Press q^F5$64=.

Natural Textbook Display™ templates can be stacked
inside one another to allow input of complicatedexpressions such as this quotient of rational exponentials.
Press a3^a1$2$$$3^2=.
(Note: the calculator does not generate a Syntax Error when the - key is used to createa negative sign. Both - and z are acceptable for use.)
In a trigonometry setting, arithmetic can be performed interms of π. Press a3qKC$4$+2qKC=.

Other useful Natural Textbook Display™ templates that help
overcome typical calculator input frustrations include:
logarithms of any base,ia1$2$$16=4fx-991EX Quick Start Guide

CALCULATE...summation (sigma) notation,
qxIxd+1$-3$7=…derivatives of a function at a specific point (value),
qyY4xd-5x$0.2=…and definite integrals.
ya1$x$$2$5=.

Settings for the “Calculate” mode can be accessed by pressing
qp(SET UP).
Press R one or more times to reveal additional Setup options.

SOLVE
The fx-991EX can elegantly solve an equation for any unknown using Newton’s method with the SOLVE command. To
use SOLVE, first input the equation to be solved, then press qr(SOLVE).

Solve x2 + Ax + Bx = 0 for x when A = 5 and B = 6.
Enter the equation by pressing, xd+Qz(A)x+Qx(B) Qr(=)0.

fx-991EX Quick Start Guide5CALCULATE
Input an initial guess for x followed by the values of A and B.
Pressqr(SOLVE) -5p5p6p.

Arrow back up to x= and SOLVE the equation bypressing p.

To accomplish the same task and solve for A or B, enter avalue for x and a value for one of the other unknowns.
For example, to solve for A when x = 1 and B = 4, press
qr(SOLVE)1p2p4p.

Arrow back up to A= and SOLVE the equation bypressing p.

The solution also displays L – R = 0. This means that
Newton’s method of approximation is directly on -5. If L – Ris not 0, simply recalculate to get a better approximation.

6fx-991EX Quick Start Guide

CALCULATEENGINEERING CALCULATIONSThere are many menus in the fx-991EX that can handle engineering calculations. The fx-991EX has the power tohandle vectors, matrices, complex numbers and numerically calculatessummation and even definite integrals.
From the Main Menu, use the arrow keys to highlight theCalculate icon and press p or press 1.

There are many different types of unit conversions that canbe accomplished on this menu. To view the options, press
q8(CONV). Use the down arrow key (R) to see all thepossibilities.
Each one of the choices has a wide range of conversion options
for many different types of unit conversion.

Use the arrow keys to locate the Length conversion and press1.

To convert 500 inches (in) into centimeters (cm), press C toreturn to the initial Calculate screen.

Press 500q8(CONV)1(Length)1(in : cm)p.

fx-991EX Quick Start Guide7

CALCULATE
To find the difference between one US Gallon and one UK
Gallon, first, convert to a common unit, like a liter (L).
Press 1q8(CONV)3(Volume)1(gal(US) : L)p.
One US gallon is approximately 3.785 L.
Now, convert the solution to gallons UK.
Press q8(CONV)3(Volume)4(L : gal(UK))p.
It looks like a US gallon is smaller.
1 US gallon = 0.8326742321 UK gallons.

The same calculation can be accomplished using astring of conversions.
Press 1q8(CONV)3(Volume)1(gal(US) : L)q8(CONV)
3(Volume)4(L: gal(UK))p.
ENGINEERING NOTATION
Converting large numbers into scientific and engineering notations
can be accomplished through a short series of keystrokes.
Start with a large number like 2.5 X 109.
Press 2.5K9p.

The gap between digits at place value separation can be viewed
by entering Set Up. Press qp(SET UP) and use the arrow
keys to navigate to the third menu.

8fx-991EX Quick Start GuideCALCULATE
Press 4(Digit Separator)1(On) to turn on the Digit Separator
to show separation between place values.

Press p to recalculate the result and display clear place value
separation.

To convert this solution into engineering notation, use the b
key to change the solution into scientific notation. To move thedecimal to the right, press b.

To move the decimal to the left, press qbX.

Calculating with engineering symbols has never been easier.
To turn on the engineering symbols in setup, press
qw(SET UP).

Select 4(Engineer Symbol)1(On) to turn on theEngineering Symbols.

fx-991EX Quick Start Guide9CALCULATE
To calculate 500k (kilo) + 10M (Mega), press
500i3(Engineering Symbols)
6(k)+10i3(Engineering Symbols)
7(M)p.
The solution is displayed using the appropriate units.

Now, use the b key to convert between units.

10fx-991EX Quick Start Guide