A Tangled Tale is a collection of ten brief humorous stories by Lewis Carroll (Charles Lutwidge Dodgson), published serially between April 1880 and March 1885 in The Monthly Packet magazine. Arthur B. Frost added illustrations when the series was printed in book form. The stories, or Knots as Carroll calls them, present mathematical problems. In a later issue, Carroll gives the solution to a Knot and discusses readers' answers. The mathematical interpretations of the Knots are not always straightforward. The ribbing of readers answering wrongly - giving their names - was not always well received. (from wikipedia)