Lewis Carroll (1832&ndash;1898) made his name with his Alice books in the 1860s, but also wrote on popular mathematics &ndash; he was a maths tutor in various capacities at Christ Church College, Oxford, from his undergraduate days until his death.<br /><br />First published in 1885, &quot;A Tangled Tale&quot; is a collection of ten brief humorous puzzles &ndash; called &lsquo;knots&rsquo; &ndash; originally published in a monthly magazine in the early 1880s. Each puzzle is described in story form, then summarised as a &lsquo;maths problem&rsquo;. For the book, Carroll assessed answers sent in by readers, referring to them by name (usually pseudonyms) and grading them, with comments in typically polite-but-cutting Oxford-don fashion.