Mr. Gates says he reads about 50 books in a year, eschewing digital readers for old-fashioned books on paper. When he is busy with work, he reads about a book or two a week but will consume four or five in the same period while vacationing with family.
Let’s say he works two-thirds of the year or 35 weeks and vacations the other 17.
That would be (35 x 1.5) + (17x 4.5) or 52.5 + 76.5 or 129.
[Related: The Math-Class Paradox.]