My explanation is a lot to read but there isn't much one must remember to use the algorithm.

DOW for last day in February = DD (Doomsday)

4/4, 6/6, 8/8, 10/10, and 12/12 are DD

I work from 9 to 5 in the 7-11

5/9, 9/5, 7/11 and 11/7 are DD

3/14 (pi day) is always a DD

1/3 is DD three years out of four, the non-leap years. It's 1/4 only in the fourth year, the leap years divisible by 4.