For instance, I was born on August 1, 1974. That was a Thursday. I figured that out in my head, muthafucka!
July 4, 1776 was also a Thursday. Wanna know how that's done? Ok... I'll tell you.
Doomsday for 1900 was a Wednesday. That's just a fact. So, that means that doomsday for 1800 was a Friday and for 1700 it was a Sunday. Now, the formula for figuring out Doomsday for a given year in the 1700's is to take the required year (76), divide by 12 (6, with a remainder of 2). Take that remainder and divide by four (0). Add those three numbers up (6 + 2 + 0 = 8), divide by seven, take the remainder (1) and add that many days to the day of the week Doomsday is on for the century year (Doomsday 1700 is Wednesday, add one, so Doomsday 1776 is a Thursday). Now, the Doomsday for July is the 11th, which means that July 11th, 1776 is a Thursday. Go back exactly 7 days to get to July 4th and that will also be on a Wednesday. IT'S THAT EASY!
Doomsday is neat!