HP 20B

Mathematical Calculations
29
To find a percentage of a given number, enter the number and multiply it by the desired percentage, followed by =. For
example, to find 25% of 200, press 200*25%= to return a result of 50 .
To add or subtract a percentage of a number, enter the first number, followed by + or - and the percentage followed
by %. Finish your calculation with =. For example, to add 10% to 50, press 50+10%= to
return a result of 55 .
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.
For example, 200I25% returns 50 , but 200 is still on Level 2 of the stack, and pressing -
returns 150 , or 200-25%.