Thane Plambeck wrote on 06/27/2004, about "Knuth Vol 4" preview material: Here's a puzzle from it [rated 25 on the Knuth scale] What is the 7.2.1.2.26: What is the unique alphametic solution to NIIHAU \pm KAUAI \pm OAHU \pm MOLOKAI \pm LANAI \pm MAUI \pm HAWAII = 0? (\pm : "plus or minus") This is an especially nice puzzle, because there is also a (different) unique answer if the "= zero" is mis-read as "= the letter O". -- Mike