In reply to Jenni.

Yes! Multiplying by one in various guises is a cool trick that I use often. In addition to t is useful for simplifying trig identities and solving integrals. And, of course, it is the basis for adding fractions by finding a common denominator.

By the way, I learned the name "dimensional analysis" for converting units. Chemists call it "stoichiometry." Both sound scarier than "multiplying by one."