This is a good article, but the very first example is perhaps a bit ill-chosen. The mass-energy equivalence formula doesn't assign mc^2 to e, it states that the

This is a good article, but the very first example is perhaps a bit ill-chosen. The mass-energy equivalence formula doesn't assign mc^2 to e, it states that the two sides are always equal. The equality operator (== in C), would probably be more appropriate.