The Last X Register - HP 33s User Manual

During program entry,
Å
cancels program entry.
During digit entry,
If the display shows a labeled number (such as  ), pressing
~
or cancels that display and shows the X–register.
When viewing an equation,
to allow for editing.
During equation entry,
function at a time.
For example, if you intended to enter 1 and 3 but mistakenly entered 1 and 2, this
is what you should do to correct your error:
T
Z
Y
X
1
1
1. Lifts the stack
2. Lifts the stack and replicates the X–register.
3. Overwrites the X–register.
4. Clears x by overwriting it with zero.
5. Overwrites x (replaces the zero.)

The LAST X Register

The LAST X register is a companion to the stack: it holds the number that was in the
X–register before the last numeric function was executed. (A numeric function is an
operation that produces a result from another number or numbers, such as
¹ Í
Pressing
This ability to retrieve the "last x" has two main uses:
1. Correcting errors.
~
deletes the currently–displayed program line and
~
backspaces over the displayed number.
~
displays the cursor at the end the equation
~
backspaces over the displayed equation, one
1
1
2 3
returns this value into the X–register.
RPN: The Automatic Memory Stack
1
1
0
2
4
Å
1
3
5
?
.)
2–7