HP -28S Manual page 71

Select Insert mode.
[ill[]
The shape of the cursor changes to an arrow, indicating that text will
be inserted to the left of the character at the cursor position.
(Pressing
[ill[]
a second time returns to replace mode, where text re-
places the character at the cursor position.)
Key in the second term for R3.
G .000rn
R3
Replace the expression in level 1 by the edited expression in the com-
mand line.
I
ENTER
I
2: 16.25
1:
I
R1+INV( INV(R2)+INV(
R3)+INV(R3»
I
EDlEmImIll _ _ _
Store the new expression in a variable EQ2.
~--------------------~
[']EQ2IsTOI 3: 12
2: {
HOME EE
SP2 )
1: 16.25
~EDlEmImIll
_ _
Step 2: Switch to the SPI or SP2 directory, change the definition of
EQ from EQI to EQ2, and use the Solver to evaluate the expression.
For this example, use the values in SPI with the new expression.
Switch to the SPI directory.
SPl
3: 12
2: {
HOME EE
SP2 )
1: 16.25
.... .:!:._--
70 4: Repeating Calculations