One-Number Functions And The Stack; Two-Number Functions And The Stack - HP 25 Owner's Handbook Manual

40
The Automatic Memory Stack
One-Number Functions
and the Stack
One-number function s execute upon the number in the X-
register only , and the contents of the Y -, Z- , and T -regi ste rs
are unaffected when a one-number function key is pre ssed.
For example , with numbers positioned in the stack as in th e
earlier exa mple , pressing th e
[ill
ke ys cha nges the stac k
contents ...
from this .. .
to this.
T
0.00
l
T
1
0 .00
z
0.00
Z
f - - -
I
lO .oo
y
314.32
Y
314.32
~
X
1-- 6 89~
Di s pl ay
X
1 26. 2~J
Display
The one-number function execute s upo n only the numbe r in the
displayed X-regi ster , and the a nswer writes over the number
that was in the X -regi ster. No other registe r is affected by a o ne-
number function .
Two-Number Functions
and the Stack
Hewlett- Packard calcul ators do arithmetic by po sitioning the
numbers in the stack the same way you would on paper. F or
instance , ifyou' wanted to add 34 and 21 you wo uld write 34 o n a
piece of paper and then write 21 underneath it , like this:
34
21
and then you would ad d, like thi s:
34
+ 21
55
Numbers are positioned the same way in the HP-25 . H ere 's
how it is don e. (If you clear the previo us numb er e ntr ies
first by pressing
a
~ th e
number s in th e stack w ill cor-
respond to those shown in the exampl e below .)