RPN: The Automatic Memory Stack 2-9
Correcting Mistakes with LAST X
Wrong Single Argument Function
If you execute the wrong single argument function, use to retrieve
the number so you can execute the correct function. (Press
first if you want to
clear the incorrect result from the stack.)
Since and don't cause the stack to drop, you can recover
from these functions in the same manner as from single argument functions.
Example:
Suppose that you had just computed ln 4.7839 × (3.879 × 10
5
) and wanted to find
its square root, but pressed
by mistake. You don't have to start over! To find
the correct result, press
.
Mistakes with Two Argument Functions
If you make a mistake with a two argument operation (such as
, ), or x),
you can correct it by using
and the inverse of the two argument
operation.
1. Press to recover the second number (x just before the operation).
2. Execute the inverse operation. This returns the number that was originally first.
The second number is still in the LAST X register. Then:
If you had used the wrong function, press
again to restore the
original stack contents. Now execute the correct function.
If you had used the wrong second number, key in the correct one and
execute the function.
If you had used the wrong first number, key in the correct first number, press
to recover the second number, and execute the function again.
(Press
first if you want to clear the incorrect result from the stack.)
