HP 30b Business Professional Calculator - Manual (Page 14)

Basic Features 6
Annunciators
Annunciators are symbols that appear in the display as messages, or after certain keys or key
combinations have been pressed. Annunciators are special symbols indicating a specific
status in the calculator. Figure 3 illustrates the annunciator symbols in the display.
Figure 3 Annunciator Symbols in the Screen Display
The Input Key
The
I
key is used to input values for variables and execute menu items.
The
I
key is also used in Reverse Polish Notation (RPN) mode to enter a number on
the stack or duplicate it.
The Equals Key
The
=
key is used at the end of a mathematical operation to calculate the final result. For
example,
1+2=
returns a final result of 3.
The
=
key, when pressed outside of a mathematical operation, also allows you to request
a calculation for the value of an item. This request only applies to items that can be calculated.
Using the Input and Equals Keys
Suppose you wanted to calculate the effective interest rate for a 12% nominal interest rate with
12 payments per year in the Interest Conversion (IConv) menu. To open the IConv menu, press
:&
. Nom %= displays on the top line, and the current value assigned to the nominal
Valid item for the
Input key
Secondary
function active
Valid item for
the Equals key
RPN mode
active
Number recall
active
Low batteries
Radians active
Begin mode
active
Number storage
active
360 day-count calendar active
Assigned value