Correcting
Mistakes
With
ill
lastx
Wrong
One-Number Function. If
you
execute
the
wrong
one-
number
function,
useHilastx Ito
retrieve
the
number
so
you
can
execute
the correct function. (Press[c]
first
if you want to clear the
incorrect result from the stack.)
Since
H|[%]
and
Ml
%chg
Idon't
cause
the
stack
to
drop,
you can re
cover
from
these
functions
in
the
same
manner
as
from
one-number
functions.
Example. Suppose that you had just computed In 4.7839 x
(3.879
x
105)
and
wanted
to
find
its
square
root,
but
pressed
[£] by
mistake.
You
don't have to start
over!
To
find the correct result, just
press
UQ^st^GI].
Mistakes
With Two-Number Functions. If you make a mistake
with a two-number operation
(0,
0,0,0,
or [£))/ you can cor
rect it by using M\
lastx
I
and
the
inverse of the two-number function
(0
or
0,
0 or
0,
{w£} or
fg]):
1. Press
Hll
lastx
| 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 LASTXregister.
Then:
• If you
had
used the
wrong
function,
press
[Hi
lastx Iagain 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 Hi
lastx
Ito recover the second number,
and
execute the func
tion again. (Pressfc1
first
if you want to clear the incorrect result from
the
stack.)
Example.
Suppose you
made
a mistake
while
calculating
16
x
19
=
304.
There are three kinds of mistakes you could have made:
42
2:
The
Automatic
Memory
Stack