Section 2: Memory Stack, LAST X, and Data Storage  23 
 
you do not need to use v. Why? Executing most HP-10C functions has 
two results: 
1.  The specified function is executed. 
2.  The  automatic  memory  stack  is  enabled;  that  is,  the  stack  will  lift 
automatically when the next number is keyed in or recalled. 
 
There  are  four  functions—v,  `,  z,  and  w—which  disable  the 
stack. They do not provide for the lifting of the stack when the next number is 
keyed in or recalled. Following the execution of one of these functions, a new 
number  will  simply  write  over  the  currently  displayed  number  instead  of 
causing  the stack to  lift. (Although the stack lifts  when  v is  pressed, it 
will  not  lift  when  the  next  number  is  keyed  in  or  recalled.  The  operation  of 
v illustrated on page 21 shows how v disables the stack.) In most 
cases, the above effects will come so naturally that you won't even think about 
them.
*
 
Two-Number Functions 
An important aspect of two-number functions is the positioning of the numbers 
in  the  stack.  To  execute  an  arithmetic  function,  the  numbers  should  be 
positioned in the stack in the same way that you would vertically position them 
on paper. For example: 
 
The numbers are positioned in the calculator in the same way, with the first (or 
top)  number  in  the  Y-register,  and  the  second  (or  bottom)  number  in  the  X-
register. When  the arithmetic operation is performed, the stack drops, leaving 
the  result  in  the  X-register.  Here  is  how  an  entire  subtraction  operation  is 
executed: 
         
*
 For a further discussion of the stack, refer to appendix A.