HP HP-21 - Page 37

Press
45
55
Display
80.00
9600.00
0
i
The next number is keyed into X.
The intermediate result of the
addition operation is displayed.
The next number is keyed into X.
The multiplication operation cannot
be performed yet, so you press ElEL.
The next number is keyed into X.
The addition operation is
performed next.
The answer is calculated without
repositioning the numbers.
Of course, you don’t have to work problems from left to right.
Most people start at the innermost parentheses and work out-
ward, keying in numbers as they need them. Either way, the
more complex the problem, the more you’ll appreciate the
capabilities of the automatic memory stack. Try this addi-
tional example.
Example: Calculate 5 x [(3+4) + (5+2) + (4+3)] = (3 x .213).
3
1S =T
[T
T
I
0.75 (3+4)
(5+2)
3+4) + (5+2)
(4+3)
3+4) + (5+2) + (4+3)