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

• 0:04
  Speaker 1: Hey, and welcome to the Short Stuff. I'm Josh, and
• 0:06
  Speaker 1: there's Chuck, and this is short Stuff, and we are
• 0:08
  Speaker 1: going to talk about something that has been overlooked for
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  Speaker 1: far too long, which is the origins of the plus
• 0:15
  Speaker 1: minus multiplication, division and equal symbols.
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  Speaker 2: I thought this was really cool by the way you
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  Speaker 2: put this together with help from FASCO, cal Tech, Science ABC,
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  Speaker 2: among other places. And I had never thought about this
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  Speaker 2: stuff because I'm not a math person, but I love
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  Speaker 2: origin stories, and I thought this is really neat, especially
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  Speaker 2: the fact that these symbols came about to begin with,
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  Speaker 2: because people before they had these. You wrote out a
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  Speaker 2: math problem like this long word problem, but not like
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  Speaker 2: you know, a train's traveling in this direction kind of thing.
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  Speaker 2: It's more like I have divided ten into two parts
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  Speaker 2: and multiplying one of these by the other. The results
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  Speaker 2: was twenty one. Then you know that one of the
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  Speaker 2: parts is thing and the other is ten minus thing.
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  Speaker 1: Right. That was an excerpt from a ninth century algebra
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  Speaker 1: book by the mathematician Mohammed ibn Musai al Kharazmi. I'm
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  Speaker 1: pretty sure that's his name. Today you would take that
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  Speaker 1: same formula and write it out as x times ten
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  Speaker 1: minus x equals twenty one.
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  Speaker 3: Yeah, so simple, that's it.
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  Speaker 1: And that reveals why these things were so important. It
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  Speaker 1: just saves you so much time. So not only did
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  Speaker 1: it make writing an algebra book that much more attractive,
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  Speaker 1: it made teaching it that much faster. You might not
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  Speaker 1: have necessarily learned it any faster, but you definitely could
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  Speaker 1: teach these things faster with these notations rather than writing
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  Speaker 1: it out. And I also saw check that some of
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  Speaker 1: those sentences that they would write, some people would put
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  Speaker 1: it into verse metered verse like poems. That takes a
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  Speaker 1: lot of time, and it's unnecessary.
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  Speaker 2: Yeah, and especially at the time when you're writing with eagles,
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  Speaker 2: feather and an ink. Weell sure, you know what I mean.
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  Speaker 1: That really drags too.
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  Speaker 3: It's not like you're just dashing this stuff off with
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  Speaker 3: a pencil.
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  Speaker 1: Nope.
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  Speaker 3: So some folks came along and changed all that.
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  Speaker 2: According to the v NR Concise Encyclopedia of Mathematics hot Read,
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  Speaker 2: the origin of the equal sign goes like this. A
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  Speaker 2: man named Robert record or record A was the royal
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  Speaker 2: court physician for King Edward about six and Queen Mary,
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  Speaker 2: and a very influential mathematician in Wales, and he got
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  Speaker 2: tired of writing out equals over and over, so he
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  Speaker 2: thus proposed the equal sign because it is two little
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  Speaker 2: equal lines, and that's parallel equal lines.
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  Speaker 3: And this I never thought it, but it's brilliant.
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  Speaker 1: Yeah, he said, a pair of parallels or twin lines
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  Speaker 1: of one length, and then he spelled. He shows what
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  Speaker 1: he's talking about, because no two things can be more equal.
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  Speaker 1: And there's a lot of extra vowels in those words,
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  Speaker 1: but yeah, he gets the point across. And he was saying, like,
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  Speaker 1: this is such a great time saver. I'm so tired
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  Speaker 1: of saying is equal to? And he wrote it in
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  Speaker 1: a book called The Wetstone of Wit, And of course
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  Speaker 1: a whetstone is what you sharpened things with, so it
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  Speaker 1: sharpens your wit to read this book. I love that title,
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  Speaker 1: and it actually became very influential and well read as
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  Speaker 1: far as sixteenth century math books go. And Robert Record
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  Speaker 1: is credited with coming up with the minus symbol and
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  Speaker 1: introducing it to his people back then.
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  Speaker 3: The equal sign.
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  Speaker 1: You mean what I say?
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  Speaker 3: Minus sign? Oh just wait, chuck, all right, well we're there.
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  Speaker 2: Plus and minus are what we use to indicate adding
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  Speaker 2: something and subtracting something. As everyone knows they come. The
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  Speaker 2: terms themselves come from Latin, where plus means more and
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  Speaker 2: minus means less. And the other thing is the plus
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  Speaker 2: symbol itself is also from the Latin word et et,
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  Speaker 2: meaning and like this and that equals that, which is
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  Speaker 2: pretty great. So at one point there was a French
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  Speaker 2: philosopher named Nicole ors Me from the fourteenth century who
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  Speaker 2: used that plus sign as a shorthand for et, which
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  Speaker 2: is what they used to write. And at first it
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  Speaker 2: didn't take right, I think, like people weren't universally accepting this.
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  Speaker 1: Yeah, it wasn't until like the sixteenth or seventeenth century
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  Speaker 1: that it started to really kind of take off. I
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  Speaker 1: think the sixteenth century, Okay, And apparently there was competition
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  Speaker 1: at first too, that it wasn't just the plain old
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  Speaker 1: plus sign that equal cross, that there were other crosses
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  Speaker 1: in the in the running too, including the Maltese cross.
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  Speaker 1: It's a great looking cross, yeah, but it takes a
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  Speaker 1: lot more time to write the Maltese cross out than
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  Speaker 1: it does to make a plus symbol, and the whole
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  Speaker 1: point of these things was to save time. So everybody said, yeah,
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  Speaker 1: Maltese cross, we like you. But we're gonna go with
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  Speaker 1: the plus sign.
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  Speaker 3: That's right.
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  Speaker 2: So that's plus, we got equals, we got plus minus.
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  Speaker 2: Now in Europe there was an Italian mathematician named Luca Pacioli,
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  Speaker 2: and Luca was using the symbol P with a little
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  Speaker 2: line over it for plus, an M with a little
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  Speaker 2: line of it over it for minus. And no one's
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  Speaker 2: exactly sure, but it seems to be that the M
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  Speaker 2: was just dropped right, and then the minus sign, because
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  Speaker 2: we already had a plus sign, became the minus sign.
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  Speaker 1: Yeah, so you don't need the plus sign forget you
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  Speaker 1: P with the tilbey over it. We're gonna take the
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  Speaker 1: M instead. And it was it wasn't Robert Record who
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  Speaker 1: came up with that, but he was the one who
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  Speaker 1: introduced it.
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  Speaker 3: To England, right, And I never knew it was called
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  Speaker 3: it tild.
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  Speaker 1: I didn't either that line over the P or the M. Yeah,
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  Speaker 1: I think that's what they call it, so yeah, And
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  Speaker 1: I don't know if it's the minus sign itself is
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  Speaker 1: called that, or if it has to be over the
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  Speaker 1: letter to be called that.
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  Speaker 2: All right, Well, there are a couple of other words
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  Speaker 2: that I did not know coming up right after the break,
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  Speaker 2: all right, we're gonna wind it out with the multiplication
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  Speaker 2: symbol and the division symbol multiplication. If you say it's
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  Speaker 2: a little X, you're incorrect because it is not an X.
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  Speaker 2: It's actually called the Cross of San Andreas because X.
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  Speaker 2: Well not because, but it would be very confusing because
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  Speaker 2: X is already a thing in math, Like you're solving
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  Speaker 2: for X. X represents something in math, So it's it's
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  Speaker 2: actually incorrect to say it's a little X.
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  Speaker 1: Yeah, if you do that at a math conference, they
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  Speaker 1: will find the nearest fire hose and flood you mercilessly
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  Speaker 1: with it.
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  Speaker 3: They will.
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  Speaker 1: So, yeah, that makes total sense. And it was a
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  Speaker 1: guy named William Autred who was writing in I think
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  Speaker 1: the sixteenth century, like the sixteen thirties, and he was
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  Speaker 1: the one who introduced it. He's credited with this. But
• 7:32
  Speaker 1: the people at Science ABC went to the trouble of
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  Speaker 1: digging up the fact that there's an anonymous appendix in
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  Speaker 1: a translation of another book of logarithms from sixteen eighteen
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  Speaker 1: where the Cross of San Andreas is first used.
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  Speaker 2: Okay, so, but he introduced it in before that, right, no.
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  Speaker 1: After, But since it was anonymous in the appendix, they
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  Speaker 1: don't know who to credit it with, and I said,
• 8:00
  Speaker 1: you need to win today. We're going to with that.
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  Speaker 2: I mentioned before the break that there were a couple
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  Speaker 2: of more words that I didn't realize were words, and
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  Speaker 2: that is the the division symbol that apparently I didn't
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  Speaker 2: even know this is not even really used anymore officially,
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  Speaker 2: which is to say, the line like the minus symbol
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  Speaker 2: with a dot above it and a dot below it
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  Speaker 2: in the center, that is actually called an obelis.
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  Speaker 1: Yeah, that symbol. You know what, it reminds me of
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  Speaker 1: of that calculator that was shaped like a big plastic owl. Oh,
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  Speaker 1: that's what I associate that with. I remember those, But
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  Speaker 1: I didn't know it was called an obelis either. And
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  Speaker 1: I also didn't know that obelis is an old Greek
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  Speaker 1: word for sharpened stick, and that that division symbol, the
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  Speaker 1: obelis is supposed to represent a small dagger.
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  Speaker 3: Yeah, it looks like one.
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  Speaker 1: So I guess what it's doing is it's cutting in half.
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  Speaker 1: It's cutting a portion out. Ah, that's the only thing
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  Speaker 1: I can come up with.
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  Speaker 3: Okay, I like that though, sure.
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  Speaker 1: And we can thank Johann Ron, who's Swiss not Swedish,
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  Speaker 1: who started using it all the way back in sixteen
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  Speaker 1: fifty nine.
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  Speaker 3: That's right.
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  Speaker 2: The other word I did not know is the what
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  Speaker 2: is now the backslash symbol for division is called a
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  Speaker 2: either a fraction bar or a solidus.
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  Speaker 1: Yeah, didn't know that either.
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  Speaker 2: I didn't know that that was the exclusive thing. Now,
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  Speaker 2: this is how out of touch with matth iron.
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  Speaker 1: Yeah. Apparently the ISO, the International Organization for Standardization, who
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  Speaker 1: aren't familiar with how to create an acronym. They said
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  Speaker 1: that you could only use the solidus or the fraction
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  Speaker 1: bar to indicate division, and that the obelis is out
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  Speaker 1: out out. But Science ABC said, don't worry everybody. Listen,
• 9:46
  Speaker 1: if you go on to your keyboard, you know what's weird.
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  Speaker 1: I haven't tried this. Did you try it?
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  Speaker 2: No?
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  Speaker 1: I'm going to try it right now. Why don't you
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  Speaker 1: go ahead and tell everybody what you're supposed to do
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  Speaker 1: and I'm going to try it myself.
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  Speaker 2: Chuck, Well, what you do is you hold the alt
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  Speaker 2: key on your keyboard and then press two four to
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  Speaker 2: six on the number pad.
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  Speaker 3: And what do we got? My friend?
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  Speaker 1: I think maybe you have to press it at once,
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  Speaker 1: hold on two four six. You got lies? That's what
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  Speaker 1: you got Chuck thirty lies.
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  Speaker 2: Oh well, let me try then you talked for a second.
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  Speaker 1: Okay, So I'm going to do it again, two four
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  Speaker 1: six with all pressed at the same time in Microsoft Word.
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  Speaker 1: The current version of Microsoft Word won't do it.
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  Speaker 3: I don't even know if I have Word on this laptop.
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  Speaker 1: The thing that gives it away for why I think
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  Speaker 1: this might not be correct any longer, is that they
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  Speaker 1: mentioned that you press the numbers two four six on
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  Speaker 1: your number pad. Remember when numbers used to be off
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  Speaker 1: to the side on a keyboard and their own thing.
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  Speaker 2: Well, I've got a keyboard like that. Okay, let me
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  Speaker 2: let me try it for you. So all to two
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  Speaker 2: four six.
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  Speaker 1: Yeah, I think at the same time.
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  Speaker 2: Oh that's hard to do. I'm trying to, like fingering
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  Speaker 2: a weird guitar chord that didn't work alt two for six.
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  Speaker 3: Right, this is just bs.
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  Speaker 1: They got us, Chuck. They got us as good as
• 11:12
  Speaker 1: Debbie Ranka did with that whole thing about Judas spilling
• 11:14
  Speaker 1: the salt shaker in the Last Supper.
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  Speaker 2: Wait, let me try one more thing, two for six.
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  Speaker 2: Now it's not working.
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  Speaker 1: Okay. Well, I'm sorry everybody that we misled you, but
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  Speaker 1: I'm glad we worked it out so you don't have
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  Speaker 1: to email us about it.
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  Speaker 3: Yeah.
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  Speaker 2: Maybe someone knows though, and can tell us what we're
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  Speaker 2: doing wrong.
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  Speaker 1: Yeah, we love hearing that, and while we wait for
• 11:35
  Speaker 1: you to write in short, stuff is out.
• 11:41
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• 11:43
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• 11:48
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