HP (Hewlett-Packard) F2215AA#ABA Calculator User Manual


 
6-14 Entering and Evaluating Equations
To change the number, type the new number and press . This new
number writes over the old value in the X–register. You can enter a number as
a fraction if you want. If you need to calculate a number, use normal
keyboard calculations, then press
. For example, you can press 2
5  in RPN mode, or press 2 5 in ALG
mode. Before pressing
, the expression will display in line 2, and
after pressing
, the result of the expression will display in line 2.
To cancel the prompt, press
. The current value for the variable remains in
the X–register and displays in right-side of the line two. If you press
during digit entry, it clears the number to zero. Press
again to cancel the
prompt.
To display digits hidden by the prompt, press
.
In RPN mode,each prompt puts the variable value in the X–register and disables
stack lift. If you type a number at the prompt, it replaces the value in the X–register.
When you press
, stack lift is enabled, so the value is saved on the stack.
The Syntax of Equations
Equations follow certain conventions that determine how they're evaluated:
How operators interact.
What functions are valid in equations.
How equations are checked for syntax errors.
Operator Precedence
Operators in an equation are processed in a certain order that makes the
evaluation logical and predictable: