==> references/books/bloopers.s <==
geometry/fence.s

Charles W. Trigg, Mathematical Quickies, Dover, 1985, #93

logic/hundred.s

Angela Dunn, ed., Mathematical Bafflers, Dover, 1980, p. 112
David Wells, The Penguin Book of Curious and Interesting Puzzles, Penguin,
    1992, #373 & #554