Order of Calculation
In chapter 1 we recommended solving chain calculations by working
from the innermost parentheses outward. However, you can also
choose to work problems in a left-to-right order.
For example, in chapter 1 you calculated:
4 -^ [14 + (7 x 3) - 2]
by starting with the innermost parentheses (7 x 3) and working out
ward—just as you would with pencil and paper. The keystrokes were:
7 IENTER I 3 014 0 2 0 4 £*2 0.
Working the problem left-to-right, the solution would be:
4 |ENTER |14|ENTER I7 I ENTER I3 0 0 2 00,
which takes one additional keystroke. Notice that the first intermedi
ate result is still the innermost parentheses: (7 x 3). The advantage to
working a problem left-to-right is that you don't have to use |x$yl to
reposition operands for noncommutative functions (0 and 0).
The first method (starting with the innermost parentheses) is often
• It takes fewer keystrokes.
• It requires fewer registers in the stack.
When using a left-to-right method, be sure that no more than four
intermediate numbers (or results) will be needed at one time, since the
stack can hold no more than four numbers at once. This example,
when solved left-to-right, needed all the registers in the stack at one
4 -r [14 + (7 x 3) - 2]
2: The Automatic Memory Stack