Test ideas for testing a percent calculation formula


I am trying to get some testideas for testing a percent calculation formula
100 * (1 - discounted_price / original_price) = discount
100 * (1 - 11.00/13.00) = 15.38

I was thinking about looking at the different boundaries using “boundary value analysis” concept but was wondering if any of you have had the opportunity to test this function before and if so which test ideas you have had and explored?

Friendly regards,


The big focus area for me on these kind of things, especially being in finance, is around rounding and precision. Notably, do you round up or down for the last significant digit?

The problem as specified is a little unusual in that it’s backwards from the usual case (i.e. generally the percent change is an input, and the result with the percent change applied is the output).