HP HP-28S - Clearing Objects from the Stack

Subtract 25 from 30.
The result is 5.
Clearing Objects From the Stack
As you worked these examples, you accumulated quite a few numbers
on the stack. The stack grows without limit as you put more objects
on the stack, and those objects remain until you use them in an oper-
ation or until you clear them.
You can clear objects one at a time or all at once.
Clear the number in level 1.
3: 125
2: 7
1: 34
IiiDIi1III .. maGEJl~
Objects in higher levels move down one level each.
Clear all objects from the stack.
., CLEAR I
It's a good idea to clear the stack whenever you start a problem. As
you work on the problem you'll know that all objects on the stack are
relevant to the current problem, not left over from the previous
problem.
44 2: Doing Arithmetic