HP HP-21 - Operations; One-Number Functions

Getting Started 9
Operations
Most function keys control two functions. One of the functions
is written on the top of the key, while the other is written in blue
on the slanted face of the key.
= To select the function written on the top face of the key,
press the key.
= To select the function written in blue on the slanted face of
the key:
1. First press the blue shift key once.
2. Then press the function key.
In spite of the dozens of functions available on the HP-21 key-
board, you will find the calculator simple to operate using a
single all-encompassing rule: When you press a function key,
the calculator immediately executes the function written on
that key.
Pressing a function key tells the calculator to imme-
diately perform that function.
For example, to calculate the square root of the 148.84 now in
the calculator, merely:
Press Display
e Square root of 148.84.
is a one-number function. All function keys operate upon
either one number or two numbers at a time. No function key
operates upon more than two numbers at once.
Function keys always work with either one number or
two numbers.
One-Number Functions
To use one-number functions:
1. Key in the number.
2. Pressthe function key (or press the blue shift key, then the
function key).