HP 35s Scientific Calculator - Manual (Page 71)

Storing Data into Variables 3-7
Recall Arithmetic
Recall arithmetic uses  ,  ,  , or  to do arithmetic
in the X–register using a recalled number and to leave the result in the display. Only
the X–register is affected. The value in the variable remains the same and the result
replaces the value in the x-register.
New x = Previous x {+, –, Ч, ч} Variable
For example, suppose you want to divide the number in the X–register (3, displayed)
by the value in A(12). Press
  A. Now x = 0.25, while 12 is still in A.
Recall arithmetic saves memory in programs: using   A (one instruction)
uses half as much memory as  A,  (two instructions).
A
15
A
12
Result: 15 – 3
that is, A – x
T
t
T
t
Z
z
Z
z
Y
y
Y
y
X
3 A
X
3
A
12
A
12
T
t
T
t
Z
z
Z
z
Y
y
Y
y
Result: 3 ÷ 12
that is, x ÷ 12
X
3 A
X
0.25