Monday. This reminded Harry of something. If it was Monday -- and you could usually count on Dudley to know the days the week, because of television -- then tomorrow, Tuesday, was Harry's eleventh birthday. Of course, his birthdays were never exactly fun -- last year, the Dursleys had given him a coat hanger and a pair of Uncle Vernon's old socks. Still, you weren't eleven every day.

Harry Potter and the Philosopher's Stone - Chapter 3 : The Letters From No One
See this quote in the Pensive -