Negative; Fraction; Store; Alpha - Texas Instruments TI-82 Keystroke Manual

10 Calculator Keystroke Guide
screen, press 4; then the
display the value of the expression, .25, which of course is the decimal equivalent of
page 27

12 Negative

See 5 Negative and Subtract.
page 35

13 Fraction

Fractions may be entered into the calculator by using the division key ÷ to produce a diagonal
slash fraction bar. The TI-82 can perform operations on fractions and give answers in either
decimal or fraction form. Enter the expression
appear on the Home screen as 5/6-1/2. Press ENTER to get the decimal form of the value of
this expression (approximately .3333333333). If you prefer to get your answer in fractional form,
you must do one extra thing before pressing ENTER. To see how to get a fractional answer, either
type in the original expression again or use 2nd [ENTRY] to reproduce it on the Home screen. With
the cursor at the end of the expression, press the MATH key. Choice 1, which is already
highlighted, is ∑Frac, which converts the preceding expression to fractional form, if it can. Press 1
or ENTER (since choice 1 is already highlighted). The display will return to the Home screen,
where the fraction conversion symbol will appear after the expression: 5/6-1/2∑Frac. Now
press ENTER to see the fractional value of the expression (one-third).
page 73

14 Store

The STO > key is used to store a particular number value in a variable (letter). That is, it assigns
a specific numerical value to a letter. If you wish to make the letter B represent the value 7, then
you must store the value 7 in the letter B. To do this, first type the number 7 and then press the
STO > key. Notice that an arrow appears on screen next to the number 7. To type the letter B (or
any other letter) first press the ALPHA key. Note that the cursor has changed: there is a letter A
inside the cursor, which indicates that the calculator is in Alpha mode. You may have noticed that
letters of the alphabet appear above many of the keys on your calculator. When the calculator is
in Alpha mode, as it is now, and you press one of these keys, it produces on screen the letter of the
alphabet shown above the key, rather than performing its usual function. Since you want to store
the value 7 in the letter B, press the key that has the letter B printed above it: the MATRX key.
Your screen should now show 7→ → B. The calculator doesn't actually store 7 in the letter B until
you press ENTER, which you should do now. From now on, until you change the value stored in
B, the calculator assigns the value 7 to the letter B. Even turning the calculator off won't erase
this result. To type in 3B, type 3 and then press the ALPHA key to put the calculator into Alpha
mode. (When you do, the letter A should appear inside the cursor.) Then press the MATRX key,
which has the letter B printed above it. Press ENTER to display the value of 3B (3 times B), which
is 21, since 3B = 3(7) = 21.
page 82

15 Alpha

To type letters of the alphabet, which are printed above many of the keys, the calculator must be
in Alpha mode. To put the calculator in Alpha mode for one keystroke only, press the ALPHA key
1 −
key, which produces only the exponent −1, not the x. Press ENTER to
x
5
6
1
−
÷ −
by typing 5 6 1
2
1
.
4
÷
2 . The expression will