HP HP-65 - Last X

Small Numbers (Negative Exponents)
To key in negative exponents, key in the number, press EEX ,
press CHS to make the exponent negative, then key in the power
of ten. For example, key in Planck’s constant (h) — roughly,
6.625 X 10727 erg. sec. — and multiply it by 50.
Press See Displayed
6.625 EEX
27
CHS
ENTER4
50 x
If you return to BEJ (<] [2] the result is rounded to zero.
Last X
Last X is the name of the register reserved for storing the latest
value of X (the number you see in the display) just after an opera-
tion using it has been specified and prior to its use in a calculation.
Initially set to zero when the power comes on, Last X remains
unchanged until a calculation of x or X and y is attempted; at
such a time, X is first saved in Last X as an automatic prelude
to the calculation. The saved value is recallable to X (repeatedly,
if desired) by the 8 operation. Last X is useful in re-
covering from accidental wrong keystrokes such as pressing the
wrong arithmetic key or entering a wrong number. For example,
if you were performing a long calculation where you meant to
substract 3 from 12 and divided instead, you could compensate
as follows:
Press See Displayed Comments
12 ENTER® 3 + - Oops —you wanted to
subtract.
g 3.00 Retrieves last number pre-
ceding division operation.