Square Root; Add - Texas Instruments TI-82 Keystroke Manual

6 Calculator Keystroke Guide
9543÷7 = 1363.285714. Notice how in these last two computations the first displays ten digits
with eight of them to the right of the decimal point, while the last also displays ten digits but with
only six of them to the right of the decimal point.
Suppose instead that you want your calculator to automatically round computations to a fixed
number of decimal places. Press the MODE key again. The second line on the Mode screen reads
Float 0123456789. To make the calculator automatically round all calculations to two
decimal places, on the second line of the MODE screen use the arrow keys to move the blinking
cursor over the number 2 and press ENTER. Press 2nd [QUIT] to return to the Home screen. Now if
you do the same three computations above again, the calculator will display the results rounded
with only two digits to the right of the decimal point (that is, rounded to the nearest hundredth):
17÷8 = 2.13, 368÷7 = 52.57, and 9543÷7 = 1363.29. When you are through making the
calculator round to two decimal places, it would probably be best to return to the MODE menu and
change the setting back to Float.
page 4
3

Square Root

The square root is the second function on the x
2
the x key in light blue print.) To produce a square root sign on the Home screen display, first
press the light blue 2nd key and then press the x
root sign. In the future, this key sequence will be denoted 2nd [
the key is enclosed in brackets. Other keystrokes involving the 2nd key will be denoted in a similar
fashion. The expression in the brackets should be found printed above one of the keys on the
keyboard.
Unlike with most scientific calculators, with the graphing calculator you enter the square root
sign first. To find the square root of 324, use the following keystrokes: 2nd [
Home screen you will see
right of the screen after you pressed ENTER.
Note that the calculator only does the square root of the number immediately following the
square root sign. If you want to compute
(7+18), to assure that the sum is computed before the square root is taken. (The correct value
ð
of this expression is 5.)
page 11
4

Add

The addition key + is on the right-hand side of the keyboard with the other basic operation keys
(subtraction, multiplication, and division). Basic addition is done as it is on most other kinds of
calculators: the expression containing addition may be entered just as it appears in print or when
written by hand. To evaluate the expression once you have typed it in, press ENTER. For example,
to evaluate 7 + 15, type this expression just as it appears and press ENTER to display the value
22.
To add expressions involving negative numbers, such as 5 + (−8), you may type this
expression just as it appears, using the parenthesis keys, and pressing ENTER to obtain the value
−3. Be sure you use the gray negative key—not the blue-gray subtraction key—when you type in
2
key. (Note the square root sign
2
324. The value of this square root, 18, should have appeared on the
ð
7 +
18
key to produce its second function, the square
] , where the second function of
ð
, you must group the sum in parentheses,
printed above
ð
] 324 ENTER. On the
ð