January 1, 1939 was a

Sunday

How to solve: January 1, 1939

1. 1
   Century anchor1900s→Wednesday (3)
   Practice →
2. 2
   Divide by 1239 ÷ 12→3
   Practice →
3. 3
   Remainder of 1239 % 12→3
   Practice →
4. 4
   Divide remainder by 43 ÷ 4→0
   Practice →
5. 5
   Year's doomsday(3 + 3 + 3 + 0) % 7→2 → Tuesday
   Practice →
6. 6
   Month doomsdayJanuary→3rd
   Practice →
7. 7
   Distance1 − 3→-2
   Practice →
8. 8
   Final answer(2 + -2) % 7→0 → Sunday