December 10, 1815 was a

Sunday

How to solve: December 10, 1815

1. 1
   Century anchor1800s→Friday (5)
   Practice →
2. 2
   Divide by 1215 ÷ 12→1
   Practice →
3. 3
   Remainder of 1215 % 12→3
   Practice →
4. 4
   Divide remainder by 43 ÷ 4→0
   Practice →
5. 5
   Year's doomsday(5 + 1 + 3 + 0) % 7→2 → Tuesday
   Practice →
6. 6
   Month doomsdayDecember→12th
   Practice →
7. 7
   Distance10 − 12→-2
   Practice →
8. 8
   Final answer(2 + -2) % 7→0 → Sunday