Fast way to find the day

The Internet is, as we all know, rife with errors. Many go uncorrected for years as long-abandoned blogs linger on with all their mistakes intact.

But poor research has been around a lot longer than the Web. Many books (remember books? They’re like Kindles, only made out of old bits of mashed up trees 🙂 ) also contain little gaffes and howlers. One such was a dusty old copy of ‘English Saga’, a history book by Arthur Bryant, which I found while browsing in the Waffle Library this afternoon. I’ve never read it all the way but have leafed through it a few times.

‘English Saga’, I noticed today, had a little inaccuracy in one chapter (I won’t send us all to sleep with the details) where a certain date is mentioned: Monday, February 22, 1848.

I had to read it twice just to be sure. Then I aha-ed (is that a verb? If not, it is now 🙂 ) in triumph. You old fool, Bryant, I thought. Feb 22, 1848 wasn’t a Monday. It was a Tuesday!

For a few years now, I have been amusing myself by trying to work out the day of various historical dates, and I now have three methods by which to achieve this. Careful though, if you want to look up how to do it, because some online tutorials do contain errors, including one I stumbled upon only yesterday.

Here’s the quickest way to work out past dates. If you like history you’ll love this especially.

Ready? Here goes.

We’ll use February 22, 1848 as our example.

STEP 1: Take the date (22) and subtract the Month Number (in this example, it’s 1. I’ll explain further down, ok?). So to start with, 22 minus 1 is 21.

STEP 2: Next take the last two digits of the year (48) and divide by 12. That gives us 4.

STEP 3: If, in that previous step, we had had a remainder, then we would have added that on afterwards. So, for the year 1849 for instance, our answer would have been 4 plus 1.

STEP 4: Oh, and if that remainder had been a bit bigger we would have divided the remainder by 4 and added the answer to our total.

But for now things are quite simple. We have 22 minus 1, plus 4. Which gives us 25.

STEP 5: We’re almost done. Now we have to take that 25 and remove as many multiples of 7 from it as we can. Whatever remains will anable us to take the final step and find the day we are looking for.

So, 25 minus 21 (ie, three times seven) leaves 4.

STEP 6: What do we do with that 4? Well, because we are working with a date in the 1800s, we have to start with Friday (it’s all to do with something called the century’s ‘doomsday’, but don’t worry about that just now) and add 4 days.

Saturday is the first one. Sunday is the second. Monday is the third one. And the fourth brings us to Tuesday.

So we now know that February 22, 1848 must be, as I said earlier, Tuesday.

Month Numbers
You’ll need these numbers if you want to try this method for yourself.

      • Jan=3 (4 in a leap year)
      • Feb=0 (1 in a leap year)
      • March=0
      • April=4
      • May=9
      • June=6
      • July=11
      • August=8
      • September=5
      • October=10
      • November=7
      • December=12

Other Centuries
For dates in the 1800s, count forward from Friday.
For dates in the 1900s, count forward from Wednesday.
For dates in the 2000s, count forward from Tuesday.

More on days and dates in due course. It’s fascinating sutff.


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