## Twentieth century dates

For a date in the twentieth century, the method is slightly simpler than for other dates:

- Take the year number (0 for 1900, 32 for 1932, 98 for 1998 etc.) and divide it by 4 (ignore any remainder)
- Add the year number to the number calculated above
- Add the date (day of the month) to the result
- Add the month number from the table (right)
- Divide by seven, and the
**remainder**gives you the day of the week (starting with Monday as day 1):1 2 3 4 5 6 0 Mon Tue Wed Thu Fri Sat Sun

## For any Gregorian date

A similar method can be used for any day in any century AD (although remember that the Gregorian calendar was only invented in 1582!)

- Take any year (including the century, eg. 1998 not 98)
- Divide the year by 4 and ignore any remainder. Add this result onto the year
- Divide the year by 100, ignore any remainder and
**subtract**this from the total - Divide the year by 400, ignore any remainder and
**add**this to the total - Add the date (day of the month)
- Add the month number from the table as before
- Subtract 1 from the total
- This gives you the day of the week, as for the earlier method

### Example

On which day of the week was the 9th of March 1879? 1879 / 4 = 469, 1879 + 469 = 2348 1879 / 100 = 18, 2348 - 18 = 2330 1879 / 400 = 4, 2330 + 4 = 2334 2334 + 9 = 2343 Using the month number from the table, 2343 + 3 = 2346 2346 - 1 = 2345 2345 / 7 = 335 remainder 0 So, 09/03/1879 was a Sunday

The only problem with the method described above is the need for a table of month numbers. If anyone knows a better method, I would much appreciate it if you would contact me using the button below.