HP 30b - Business Professional Calculator User Manual page 34

%
In RPN mode, the key calculates x % of the number on Level 2 of the stack, when x is
the number on Level 1 of the stack. It does not modify the number on Level 2 of the stack, and
%
thus allows you to perform addition or subtraction after pressing to add or subtract x %
from the number.
200I25%
For example, returns 50, but 200 is still on Level
-
2 of the stack, and pressing returns 150, or 200-25%.
26 Mathematical Calculations