HP 15c Scientific manual Calculator Functions and the Stack, 13.9 +, 20.6475

36 Section 3: The Memory Stack, LAST X, and Data Storage

Keystrokes Display

*287.0000 Reverses the function that produced the wrong answer.

13.9 + 20.6475 The correct answer.

Calculator Functions and the Stack

When you want to key in two numbers, one after the other, you press v between entries of the numbers. However, when you want to key in a number immediately following any function (including manipulations like )), you do not need to use v. Why? Executing most HP-15C functions has this additional effect:

•The automatic memory stack is lift-enabledthat is, the stack will lift automatically when the next number is keyed or recalled into the display.

•Digit entry is terminated, so the next number starts a new entry.

T	t
Z	z
Y	y
X	4

Keys:

t

z

y

2

¤

lost

z

y

2

5

5

z

z

y

7

+

There are four functions – v, `, z, and w – that disable stack lift.* 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 simple write over the currently displayed number instead of causing the stack to lift. (Although the stack lifts when vis pressed, it will not lift when the next number is keyed in or recalled. The operation of v illustrated on page 34 shows how v thus disables the stack.) In most cases, the above effects will come so naturally that you won’t even think about them.

*− will also disable the stack lift if digit entry is terminated, making − clear the entire display like `. Otherwise, it is neutral. For a further discussion of the stack, refer to appendix B.