Stuff You Should Know - Short Stuff: Origin of Math Signs

Episode Date: September 20, 2023

Have you ever stopped mid-pencil mark and realized to your astonishment where the plus sign came from? Then this one’s for you.See omnystudio.com/listener for privacy information.

Sometimes the pop culture we love just teens hits differently in retrospect. Maybe it's a tabloid story we couldn't get enough of or an illicit student teacher relationship on our favorite show. We're Suzy Bannock-A-Rum and Jessica Bennett, posts of the new podcast in retrospect, where each week we'll revisit a cultural moment from the past that shaped us and probably you to try to understand what it taught us about the world and our place in it. You're the first person that I've talked to about this for years and years. Listen to In Retrospect on the I Heart Radio app, Apple Podcasts, or wherever you find your favorite shows. Hey and welcome to the short stuff. I'm Josh and there's Chuck and this is short stuff.

And we are going to talk about something that has been overlooked for far too long, which is the origins of the plus, minus multiplication, division, and equal symbols. I thought this was really cool, by the way. I, you put this together with help from FASCO, Caltech, Science ABC, among other places, and I had never thought about this stuff because I'm not a math person, but I love origin stories. And I thought this is really neat, especially the fact that these symbols came about to begin with because people before they had these, you wrote out a math problem like this long word problem.

But not like, you know, a train's traveling in this direction kind of thing. It's more like, I have divided 10 into two parts and multiplying one of these by the other. The result was 21. Then you know that one of the parts is thing and the other is 10 minus thing. Right. That was an excerpt from a 9th century algebra book by the mathematician Muhammad Ibn Musa al-Kar was me. I'm pretty sure that's his name. Today you would take that same formula and write it out as x times 10 minus x equals 21. Yeah, so simple. That's it. And that reveals why these things were so important.

It just saves you so much time. So not only did it make writing an algebra book that much more attractive, it made teaching it that much faster. You might not have necessarily learned it any faster, but you definitely could teach these things faster with these notations rather than writing it out. And I also saw a check that some of the,

those sentences that they would write, some people would put it into verse, metered verse, like poems. That takes a lot of time and it's unnecessary. Yeah, and especially at the time when you're writing with a eagle's feather and an ink well. Sure. You know what I mean?

That really drags too. It's not like you're just dashing this stuff off with awell. Sure. You know what I mean? That really drags too. There's not like you just dashing this stuff off with a pencil. Nope. So some folks came along and changed all that. According to the VNR concise encyclopedia of mathematics, hotread. The origin of the equal sign goes like this. A man named Robert Record or Record A was the Royal Court Physician for King Edward, the Bup-Bup-Bup 6, and Queen Mary, and very influential mathematician and whales, and he got tired of writing out equals over and over. So he thus proposed the equal sign because it is two little equal lines. And

that's parallel equal lines. And that's I never thought about it, but it's brilliant. Yeah, he said a pair of parallels or twin lines of one length. And then he's spelled, he shows what he's talking about. Because no two things can be more equal. And there's a lot of extra vowels in those words, but he gets the point across. And he was saying like, this is such a great time saver. I'm so tired of saying is equal to. And he wrote it in a book called The Wet Stone of Witt. And of course, a wet stone is what you sharpen things with. So it's sharpened your wit to read this book. I love that title. And it actually became very influential and well read as far as 16th century math books go. And Robert record is credited with coming

up with the minus symbol and introducing it to his people back then. They equal sign, you mean? What did I say? Minus sign. Oh, we just wait, Chuck. All right. Well, we're there. Plus and minus are what we use to indicate adding something and subtracting something as everyone knows. They come, the terms themselves come from Latin, where plus means more and minus means less. And the other thing is the plus symbol itself is also from the Latin word et, meaning and,

like this and that equals that which is pretty great. So at one point there was a French philosopher named Nicole Oresme, from the 14th century who used that plus sign as a shorthand for et which is what they used to write. And at first, it didn't take, right? I think people weren't universally accepting this. Yeah, it wasn't until the 16th or 17th century that it started to really kind of take off. I think the 16th century.

And apparently, there was competition at first too, that it wasn't just the plain old plus sign that equal cross, that there were other crosses in the running too, including the maltese cross. It's great looking cross, but it takes a lot more time to write the maltese cross out than it does to make a plus symbol. And the whole point of these things was to save time.

So everybody said, yeah, maltese cross, we like you, but we're going to go with the plus sign. That's right. So that's plus. We've equals, we got plus minus now. In Europe, there was an Italian mathematician named Luca Pacheoli. And Luca was using the symbol P with a little line over it for plus and M with a little line over it for minus. And no one's exactly sure, but it seems to be that the the the M was just

dropped right. And then the minus sign, because we already had a plus sign, became the minus sign. Yeah. So you don't need the plus sign. Forget you P with the tilde over it. We're going to take the M instead. And it was it wasn't Robert record who came up with that, but he was the one who introduced it to England. Right. And I never knew what's called a tilde. I didn't either. That line over the p or the m. Yeah. I think that's what they call it. So yeah. And I don't know if it's the minus sign itself is called that or if it has to be over the letter to be called that. All right, well, there are a couple of other words

that I did not know coming up right after the break. This is In Retrospect, a podcast about pop culture from the 80s and 90s that shaped us. I'm very much a product of the pop culture I consumed. Yeah. And I don't think that's a bad thing. I'm Jessica Bennett, a New York Times writer and bestselling author. I'm Susie Bette-Keram, an award-winning TV producer and filmmaker. Every week, we'll revisit a moment in cultural history that we just can't stop thinking about.

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I want you to really smell the ax body spray that emanated during this time. It was presented more as kind of like a crime topic. Okay, and that's not a long story. Not a long story. It had been branded on the uteruses of every single woman from sea to shining sea. Listen to In Retrospect on the I Heart Radio app, Apple podcasts,

or wherever you listen to your favorite chips. Just before midnight on September 8, a 6.8 magnitude earthquake rocked Morocco, killing over 1,000 people and sending thousands more into the street. Families have lost everything and are in desperate need of basic items. Care is working in the country to get emergency water, food, and medical support to survivors.

Your support will ensure that people get the urgent help they desperately need. To help, donate now at care.org slash maraco. Alright, we're going to wind it out with the multiplication symbol and the division symbol. Multiplication, if you say it's a little x, you're incorrect because it is not an x, it's actually called the cross of San Andreas because X will not because, but it would be very confusing because X is already a thing in math like you're solving for X. X represents something in math. So it's actually incorrect to say it's a little X. Yeah. If you do that at a math conference, they will find the nearest fire hose and flow you mercilessly with it. It will. So, yeah, that makes total sense. And it was a guy named William Autred, who was writing,

and I think the 16th century, like the 1630s. And he was the one who introduced it. He's credited with this. But the people at Science ABC went to the trouble of digging up the fact that there's an anonymous appendix in a translation of another book of logarithms from 1618 where the Cross of San Andreas is first used. Okay, so, but he introduced it before that, right? No, after, but since it was anonymous in the append appendix they don't know who to credit it with and outred you need to win today we're gonna

I mentioned before the break that there were a couple of more words that I didn't realize were words and that is the the division symbol that apparently I didn't even know this, is not even really used anymore officially, which is to say the line, like the minus symbol, with a dot above it and a dot below it in the center, that is actually called an obelisk. Yeah, that symbol, you know, that reminds me of that calculator that was shaped like a big plastic owl. Oh, yeah. That's what I associate that with.

I remember those. B.I. didn't know it was called an obelisk either, and I also didn't know that obelisk is an old Greek word for sharpened stick, and that that division symbol, the obelisk, is supposed to represent a small dagger. Yeah, it looks like one. So I guess what it's doing is it's cutting in half, it's cutting a portion out. Ah, that's the only thing I can come up with. Okay, I like that though.

Sure, and we can thank Johann Ron, who swissed, not Swedish, who started using it all the way back in 1659. That's right. The other word I did not know is the, what is now the backslash symbol for division is called a either a fraction bar or a solidus. Yeah, I didn't know that either. I didn't know that that was the exclusive thing now. This is how out of touch with math, I am. Yeah, apparently the ISO, the international organization for standardization

who aren't familiar with how to create an acronym. Right. They said that you can only use the solidest or the fraction bar to indicate division and that the obelis is out, out, out. Ah. But science ABC said, don't worry everybody, listen. If you go on to your keyboard, you know it's weird, I haven't tried this. Did you try it? No. I'm going to try it right now.

Why don't you go ahead and tell everybody what you're supposed to do, and I'm going to try it right now. Why don't you go ahead and tell everybody what you're supposed to do and I'm going to try it myself Chuck. Well what you do is you hold the alt key on your keyboard and then press 2, 4, 6 on the number pad. And what do we got my friend? I think maybe you have to press it at once. Hold on. 2, 4, 6. You got lies. That's what you got Chuck. Dirty lies. Well, let me try. Then you talk for a second. Okay, so I'm going to do it again. Two, four, six, with all pressed at the same time in Microsoft Word. The current version of Microsoft Word won't do it. I don't even know if I have word on this laptop.

The thing that gives it away for why I think this might not be correct any longer is that they mentioned that you press the numbers 2, 4, 6 on your number pad. Remember when numbers used to be off to the side on the keyboard and their own thing? Well, I've got a keyboard like that. So let me try it.

Let me try it for you. So all to 2, 4, 6? Yeah, I think got a keyboard like that. So let me try it. So Alt 246. Yeah, I think at the same time. That's hard to do. I'm trying to, I'm just like fingering a weird guitar chord. That didn't work. Alt 246. Right.

This is just BS. They got us, Chuck. They got us as good as Debbie Ronca did with that whole thing about Judas spilling assault shaker in the last supper. Alright, let me try one more thing. Two, four, six. Now it's not working. Okay. Well I'm sorry everybody that we misled you but I'm glad we worked it out so you don't have to email us about it. Yeah maybe someone knows though and can tell us what we're doing wrong. Yeah we we love hearing that. And while we wait for you to write in,

short stuff is out. Stuff you should know is a production of I Heart Radio. For more podcasts, my heart radio, visit the I Heart Radio app. Apple podcasts are wherever you listen to your favorite shows. you