7×8=?
Light all 45 lanterns on the 9 × 9 table.
7 × 8 and 8 × 7 share one lantern, so there are 45 facts to learn, not 81. A quick correct answer (under 5 seconds) makes a lantern brighter; three in a row lights it fully. A miss dims it a step and brings the question back a few turns later.
New questions favour the dim lanterns, so practice goes where it is needed. After each answer you see the line from the Chinese 九九歌 rhyme, and after a miss you see the fact as rows of dots.