Jikan no Muda
One of several puzzles, games, acrostics and other intellectual diversions to be found in the pages of the Times.
This appears to be a game, possibly a cultural import from the Agatean Empire, involving the arrangement of numbers in a grid according to some harmonious mathematical principle. Vetinari's record for solving the puzzle is somewhat less than seventeen seconds. He simply stares at it for a short time, then reels off the answer. Presumably, compared with Ankh-Morpork's internecine "little wheels within big wheels" analogy, simple integers that can only logically be in one place are ineffably easy.
Jikan no muda is Roundworld Japanese for "a waste of time."
Suspiciously like the number game Sudoku, which sparked a minor craze among those so inclined, mushrooming from The Times newspaper in Britain, which launched it on 12 November 2004 (calling it Su Doku) to everywhere within weeks. Retired Hong Kong judge Wayne Gould, 59, a New Zealander, saw a partly completed puzzle in a Japanese bookshop and over six years he developed a computer program to produce puzzles quickly. Knowing that British newspapers have a long history of publishing crosswords and other puzzles, he promoted Sudoku to The Times.
The rapid rise of Sudoku in Britain from relative obscurity to a front-page feature in national newspapers attracted both commentary in the media and parody, (such as when The Guardian's G2 section advertised itself as "the first newspaper supplement with a Sudoku grid on every page". Obviously, with the enormous ripples this interest caused in the space-time-continuinuumumum-thing it eventually washed over the Disc and narrative causality created the impulse for the Ankh-Morpork Times to do the same thing.
Though he excels at Jikan no Muda and can solve them after glancing at any grid for a few seconds, Vetinari actually finds them unsatisfying, as numbers are too easy to outwit. He enjoys crosswords far more, as one needs to comprehend how another person's mind works when actively trying to mislead. He has found great pleasure in the work of 'The Blind Letter Office' at the Post Office, helping to decipher the nigh-illegible gibberish that some of Ankh-Morpork's less educated citizenry address their letters with - for example working out casually that 'Duzbuns Hopsit pfarmerrsc' equals 'K. Whistler, Baker, 3 Pigsty Hill' (Those Buns Opposite the Pharmacy). The men employed for this job are successful in 'translating' five addresses out of every six.