On first inspection, the prompt seems rather trivial and easy to confirm. Yet, it has proved to hold a fascination for younger secondary school students who can verify its truth but are rarely certain that the relationship will hold for "more complicated" statements of the same type (including for percentages greater than 100). After a the period in which students ask questions and make observations about the prompt, the inquiry often involves a fast-paced period of exploration with students testing different types of numbers. Once students have explained why the prompt is true, they can extend their reasoning by comparing other statements (below) to the original prompt.
The inquiry has developed into finding fractions of amounts (and fractions of fractions) when students change the prompt. Why does 5/8 of 2/3 = 2/3 of 5/8? The prompt has, furthermore, led to students trying to express their observations algebraically.