Suppose that today is February 13, 2053. The day of the week is a Thursday. One week (seven days) from today, on February 20, 2053, it will be Thursday again. After two weeks (fourteen days), it will be Thursday once more. We need to figure out how many weeks and days will have passed after a year. 2053 is not a leap year, so 365 days will pass between February 13, 2053 and February 13, 2054. Let’s divide by 7 to find out how many weeks that is: 365 / 7 = 52, remainder 1, or fifty-two weeks with one day left over. Fifty-two weeks after February 13, 2053 is yet another Thursday, so fifty-two weeks and one day later must be a Friday.
We can use the same method for any date, but we have to be careful. Because some years are leap years, a year from today might be 366 days and not 365. For instance, there are 366 days between Saturday, November 20, 2055 and November 20, 2056, because 2056 is a leap year and February 29, 2056 lies between the two Novembers.