Author and librarian Nancy Pearl advocates the “Rule of 50.” This entails reading the first 50 pages of a book and then deciding if it is worth finishing. The Rule of 50 has an interesting feature: once you are over the age of 50, subtract your age from 100 and read that many pages. Pearl writes: “And if, at the bottom of Page 50, all you are really interested in is who marries whom, or who the murderer is, then turn to the last page and find out. If it’s not on the last page, turn to the penultimate page, or the antepenultimate page, or however far back you have to go to discover what you want to know.…When you are 51 years of age or older, subtract your age from 100, and the resulting number (which, of course, gets smaller every year) is the number of pages you should read before you can guiltlessly give up on a book.…When you turn 100, you are authorized (by the Rule of 50) to judge a book by its cover.”