HP HP-28S - Page 25

The number 30 is removed from level 1, and its sine, .5, is returned to
level
1. The previous result, 38, remains in level 2.
Calculate 38 x .5.
The numbers 38 and .5 are removed from levels 1 and 2, and their
product, 19, is returned to level 1.
This completes the calculation:
(15
+ 23) x sin 30° = 19.
To summarize, here's a general procedure for the calculation you just
completed.
1. Key a number into the command line.
2. Press I ENTER I to put a number on the stack.
3. Press the key to execute the command. (If the command doesn't
appear on the keyboard, select the menu that contains the com-
mand, and press the menu key below the appropriate menu label.)
The previous example demonstrated that all calculations occur on the
stack. To highlight this idea, you pressed I ENTER I to put every number
on the stack. In practice, you need to press I ENTER I only to separate two
numbers keyed in sequentially-in the example, to separate 15 and 23.
Try
repeating the example, omitting the second and third I ENTER Is.
24 1: Getting Started