HP 20B User Manual

Mathematical Calculations
19
When an operation is performed on the stack, addition (+)for instance, the calculator "pops" or moves the two numbers
from the bottom levels (Levels 1 and 2) out of the stack, performs the operation, and "pushes" the results back into the stack.
With the numbers entered into the stack as shown in Figure 3, pressing + changes the stack as shown in Figure 4. Note
that when the numbers are "popped" out to add 23 and 41, Level 4 of the stack remains unchanged.
-15
-15
12
64
Figure 4 The RPN Stack of Figure 3 after the Addition Operation
Last Number
Each time you perform a mathematical operation, the content of Level 1 of the stack is saved. Pressing :d recalls that
number. This functionality can be used to undo an erroneous key press, or if you want to reuse a number, such as 56.123 in
the expression:


  123.56
123.5623.1

See Table 2-2 for an example using the last number function.
Table 2-2 Last Number
Keys Display Description
:u3I
Sets FIX= to 3.000
<<<<<
II
Selects RPN as the operating mode.
O1c23
I56c1
23
Inputs 1.23 and 56.123

HP 20B Specifications

General

Type	Financial
Cover	-
Form factor	Pocket
Control type	Buttons
Product color	Black
Digits	12 digits
Display type	LCD
Display tilting	No
Display number of lines	2 lines
Battery type	CR2032
Power source	Battery
Auto power off	Yes
Number of batteries supported	2
Memory registers	110

Weight and Dimensions

Depth	149.2 mm
Width	77 mm
Height	16 mm
Weight	37.5 g