The Following procedure gives the Old Calendar date for Pascha in any year:

1. Divide the year by 4. Discard the whole number quotient. The
2. remainder = a.
3. Divide the year by 7. Discard the quotient. The remainder = b.
4. Divide the year by 19. Discard the quotient. The remainder = c.
5. Compute (19c +15) / 30. Discard the quotient. The remainder =
6. d.
7. Compute (2a + 4b - d +34) / 7. Discard the quotient. The
8. remainder = e.
9. Compute (d + e + 114) / 31. The quotient = f. The remainder =
10. g.
11. 
    "f" is the month in which Pascha occurs (3 = March; 4 = April)
12. 
    "g+1" is the day of the month.