HP 39g+ User Manual page 31

Explicit and
implicit
multiplication
H I N T
Parentheses
Getting started
Implied multiplication takes place when two operands
appear with no operator in between. If you enter AB, for
example, the result is A*B.
However, for clarity, it is better to include the
multiplication sign where you expect multiplication in an
expression. It is clearest to enter AB as A*B.
Implied multiplication will not always work as expected.
For example, entering A(B+4) will not give A*(B+4).
Instead an error message is displayed: "Invalid User
Function". This is because the calculator interprets
A(B+4) as meaning 'evaluate function A at the value
B+4', and function A does not exist. When in doubt, insert
the * sign manually.
You need to use parentheses to enclose arguments for
functions, such as SIN(45). You can omit the final
parenthesis at the end of an edit line. The calculator
inserts it automatically.
Parentheses are also important in specifying the order of
operation. Without parentheses, the hp 39g+ calculates
according to the order of algebraic precedence (the next
topic). Following are some examples using parentheses.
Entering...
45
45
85
85
Calculates...
π sin (45 + π)
π sin (45) + π
85 9
9
85 9
9
×
×
1-21