Percentage Calculator

Percentage Calculator is a free tool that is used to learn and calculate percentages. It's made around a concept of showing different (but related) formulas solved simultaneously as user fills in any 2 of the 3 fields in any of those sentences. For example: as user fills X and Y in "X% of Y is Z", the Z is calculated. 3 other sentences are being "solved" as well ("Z is X% of Y", "fraction Z/Y is the same as X%" and "Z is Q% increase/decrase from Y"). Also, few more related calculations are shown. It all sounds complicated, but it's dead simple once you look at the tool. So it provides 2 benefits: it can simply solve an percentage equasion (handy for lazy adults) and shows students how different formulas relate to each other. The tool can be embedded on 3rd party websites. This way it can provide an interactive element to otherwise dull math lessons.