HP 48g Graphing Calculator - Manual (Page 142)

Step 5: Use BOXR to calculate the ratio of surface area to volume
for a box 9 inches high, 18 inches wide, and 21 inches long.
Enter the height, width, and length, then execute BOXR.
9 (ENTER)18(ENTER)21
(VAR) B O X R
1: .4285?1428571
Note that BOXS was defined using h, lu, and I as variables, and that.
BOXS takes r, y, and
2 as arguments in the definition for BOXR. It
makes no difference if the variables in the two definitions match—each
set of variables is independent of the other.
11
11-10 Using Mathematical Functions