HP 49g Graphing Calculator - Manual (Page 41)

Multi-command calculations
Because the result of a calculation is retained on the stack, you can easily
perform complex calculations by accumulating the results of sub­
calculations on the stack and then treating these results as the arguments
m a fmther calculation.
Example:
To calculate
13^
-
(17
x
19) + |
1. Enter 1300.
The result—169—appears on level 1 of the stack.
2. Enter 17 and press (ENTER).
3. Enter 19 and press (ENT0.
4. Press ®.
The product of 17 and 19—323—appears on level 1, and the previous
result—169—is now level 2.
5. Press Q.
The two previous results—169—and 323—are now treated as the
arguments in a fmther operation. This operation replaces the
arguments with the result of the operation, that is, the difference
between the fust result and the second.
Page 4-4 The Stack