HP HP-28S - Adjusting the Display Contrast; Keyboard Calculations

The calculator beeps and displays t'le-mot- ':I Los t. The message auto-
matically disappears when you press a key.
If you begin to reset memory but change your mind, continue holding
down [
ON 1 while you press [ DEL 1 (in the top row, next to o::H§]), and
then release @ill. Pressing [ DEL 1 cancels the reset sequence.
Adjusting the Display Contrast
You can adjust the contrast of the display to compensate for various
viewing angles
and light intensities.
To adjust the contrast:
1. Press and hold [ ON I.
2. Press G one or more times to darken the display, or press G
one or more times to lighten the display.
3. Release [ ON I.
Keyboard Calculations
Try the following calculation.
(15
+ 23) x sin 30°
The basic steps are the same as using paper and pencil. First you'll
calculate 15 + 23, which produces an intermediate result. Next you'll
calculate sin 30°,
which produces the other intermediate result. Fi-
nally, you'll
combine the intermediate results for the answer.
If you make a mistake while keying in a number, you can:
• Press
[!] to erase the last digit you keyed in.
• Press
1 ON 1 to erase all the digits you keyed in.
1: Getting Started 21