Operating the TI-80  1-21
The TI
-
80 recognizes implied multiplication. For example, it
understands 
2
p
, 
4SIN 45
, 
5(1+2)
, and 
(2
×
5)7
 as implied
multiplication.
All calculations inside a pair of parentheses are completed
first. For example, in the expression 
4(1+2)
, EOS first
evaluates the portion inside the parentheses, 
1+2
, and then
multiplies the answer, 
3
, by 
4
.
You can omit any right (closing) parenthesis at the end of an
expression. All “open” parenthetical elements are closed
automatically at the end of an expression and preceding the 
!
(store) or display-conversion instructions.
Note: Parentheses are also used to enclose the arguments for
certain functions, for example, 
NDERIV(A
ñ
,A,6)
. In these
cases, parentheses do not indicate implied multiplication.
To enter a negative number, use the negation function. Press 
·
, and then enter the number. On the TI
-
80, negation is in the
fourth group in the EOS hierarchy. Functions in the first
group, such as squaring, are evaluated before negation.
For example, 
L
X
ñ
 is a negative number (or 0); 
L
9
ñ
 is 
L
81
. Use
parentheses to square a negative number: 
(
L
9)
ñ
.
Note: Use the 
|
 key for subtraction and the 
·
 key for
negation. If you press 
|
 to enter a negative number, as in 
9
 
p
|
 
7
, or if you press 
·
 to indicate subtraction, as in 
9 
·
 7
, it
is an error. If you press 
?
 
A
 
·
 
?
 
B
, it is interpreted
as implied multiplication (
A 
QL
B
).
Implied
Multiplication
Parentheses
Negation