Question

John and Jeremy are the local names for two lighthouses that guard a particularly dangerous part of the coast. John blinks every 6 seconds and Jeremy blinks every 4 seconds. They blink together at midnight. How many seconds will pass before they blink together again?

Answer 1

John blinks every 6 seconds, Jeremy every 4 seconds, so they both will blink next on a common factor of 6 and 4, or an LCD, that'd be 12 seconds later, so at 00:00:12.