I can tell you what day of the week you were born on (without looking it up)

I recently learned a new skill that I haven't shown Kim yet, I hope it surprises us. Look at this, okay, Kim. I want you to write any random date you choose. Write it in large letters on this sheet of paper. Here it is okay, uh, June 11, 1970, that's Monday. I don't know, look up, wait, where's my phone? 7 3, it's Monday like another day, how did you know that other day? How did you know? I would choose that date. I did not do it. I know you'd pick that date, wait, save this so you're dead and Browning me March 17 18 42 it's a thirsty Thursday, make one, make one in the future, make one, make one that hasn't arrived yet, any random dat Whichever you choose, how are you? doing this 2nd mhm from June 30 uh 62 oh that's a thousand years in the future okay monday monday oh my gosh very good I'm so glad I did it right is this one of those uh is it like something that Did Chris Ramsey teach you? uh, I bet Chris Ramsey knows how to do this, but it's not a magic trick, it's a legit math trick.

Incredible. I saw this skill or trick

what

ever you want to call it in the number file just a couple of

week

s ago. James Grime, who is a mathematician working in Cambridge, showed Brady Haron how to calculate the day of the

week

for any date, basically an arbitrary date, and he can do it very, very quickly, just in his head. It's a fantastic video. It's linked below. The James Grime thing is. a mathematician from Cambridge, so he's a very smart guy and that immediately made me think that I would never be able to do this, but I watched the video anyway and I followed

what

he was doing and at the end of the video I was still following him, no It seemed so complicated.

I thought it would be awesome if he could

tell

people the day of the week for whatever date they could give me, so I thought I'd give him a learning goal. I do this myself and it's actually not too difficult it all arises from a simple peculiarity in the calendar that we use basically the fourth of the fourth the six of the sixth the eighth of the eighth the 10th of the 10th and the 12th of the 12th no matter what year I mean, they all arrive on the same day in 2021, they are all Sundays, so can you imagine if someone told you April 6th, you would just add two days to make it Monday Tuesday and you could

tell

people it's a Tuesday, what What about June 10?

Well, that's 4 days ahead from here, so it's Monday Tuesday Wednesday Thursday if you can memorize these dates and you know they're all Sunday and it's pretty easy to work out what date they give you. Based on that information, what happens if the year is not 2021? Well, this is where it gets a little more complicated. Let me explain to simplify all of this. First you assign a number to each day of the week, so zero is Monday, no. zero is Sunday ignore that one is Monday Tuesday Thursday so you need to find out what day of the week all those dates I talked about before fall for that particular year that's 5 that's zero oh this is Sunday goes Sunday Friday Wednesday Tuesday Sunday Friday Wednesday Tuesday 2004 was a leap year, so we have to add five to the quarter of the fourth sixth of 6, to the ethical of e8, to 10, so every 28 years, what did I say on Thursday?

I said Thursday to then tunnel into quantum realm two for a Tuesday plus the year plus the number of leap years is zero, which equals one Sunday, so clearly I'm really bad at explaining how to figure this out, but trust me, it's not so difficult and James Grime did a fantastic job. I work to explain it in simple terms in the video of the original numerical file. I was able to follow one or two clocks and was calculating the days of the week of any arbitrary date, basically the technique you use reduces a date like January 26, 2087. down to a simple pencil and paper sum, this sum is really easy to calculate, the difficult thing is trying to do it mentally while talking and not just being 24+ 3, so easy to do, difficult to do in speed, so how did I learn well?

First, I wrote down my cheat sheets that give me all the days that fall on the same day of the week on the calendar, then I wrote down the starting points of the century and also had them cornered with the number corresponding to the day of the week. week, so I put it aside and started practicing with dates with pencil and paper trying to figure it out. I actually have a spreadsheet. I actually used the spreadsheet to generate random dates and then I put in what my guess was and it told me if I did it right or wrong, so you can see at the beginning that I'm wrong quite often, but when I did this 142 times I had a chain of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 correct guesses, so I was getting pretty good at it and I did this a total of 176 times, so I sat with headphones on one Friday night night and a Saturday morning and I guessed 176 crazy dates.

Halfway through, I put down the pen and started doing it in my head, which slowed me down a lot, but eventually I got faster and faster and more accurate until I got to the point where I could do this in person in front of someone like that. Yes, I practiced and practiced and practiced and I got faster and faster and I actually timed how long it took me. I did it in three sessions when I stopped, I stopped my stopwatch and it took me 8 hours, 32 minutes and 23 seconds to do it. It's good for telling you what day of the week is an arbitrary date.

I got really into this for some reason. I really enjoyed studying this. I don't know why I'm a nerd. uh, thank you, thank you very much for watching, I hope. Give it a try if you do, let me know in the comments and I'll see you next time.