I get asked about these all the time because they're such scary looking problems -- fractions in the numerator and denominator of even bigger fractions -- yet one simple trick works for them every time.

OOPS! To create playlists you must logged in.

If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)