The doomsday algorithm is a quick and simple way to determine the day of week of any given date. (See the Wikipedia page for more information) This trainer provides you with random dates and times your attempt at finding the day of week.
2089-09-13
Input day of week (0 for Sunday, 1 for Monday etc.): 0
Incorrect. The answer is Tuesday.
2057-06-14
Input day of week (0 for Sunday, 1 for Monday etc.): 4
Correct! Your time was 2.5611350536346436 seconds.