I want you to picture the keyboard in front of
you right now. Specifically, just look at the
number five key. Oh, yeah. Right in the middle
there. Exactly. Resting right there, just above
that digit, is this symbol that you probably
see, I don't know, every single day. Oh, without
a doubt. Right. You use it in work emails. You
rely on it to understand retail sales, your phone's
battery life, sports statistics. I'm talking,
of course, about the percent sign. It is just
a... entirely ubiquitous. I mean, it's one of
those rare symbols that effortlessly crosses
the boundary between complex mathematics and
just, you know, everyday casual conversation.
But, and this is the crazy part, that mundane,
everyday fraction of a hundred symbol, it is
hiding a completely secret history. Oh, it really
is. It's got a double, maybe even triple life.
Yeah. So today, we're going to take you on a
deep dive into the surprisingly chaotic life
of the percent sign because we're talking about,
like, lazy medieval scribes. You're a lazy stranger.
Pierce international turf wars over typography
and completely alternate identities in the underground
worlds of computer science and linguistics. It's
wild. It goes so far beyond just math. It does.
And I promise you, by the time we finish this
deep dive today, you are never going to look
at your keyboard the same way again. And as a
bonus, you're going to have the absolute ultimate
trivia. in your back pocket for your next, you
know, boring budget meeting. Always good to have
that ready to go. Right. But before we get into
the scribes and the hackers, we should probably
set the baseline. What exactly is the core function
of the percent sign? Well, at its most fundamental
level, it's simply a symbol used to indicate
a percentage, which, you know, is a number or
a ratio expressed as a fraction of 100. Right.
Out of 100. Exactly. But it actually has these
mathematical siblings that operate on the exact
same visual logic. Wait, really? Siblings? Yeah.
So, for example, there's the per mille sign.
It looks almost exactly like a percent sign,
but it has two little zeros at the bottom right
instead of one. Oh, I think I've seen that. Yeah.
It indicates a fraction per thousand. And then
if you want to go even further, there's the per
myriad. Per myriad? Yeah. Or sometimes it's called
a basis point. And that one has three zeros at
the bottom. which indicates parts per 10 ,000.
OK, let's unpack this. Because to really understand
how the standard percent sign became this global
heavyweight, we actually have to travel back
to a time before it even existed. Right, way
back. And this is where the story gets incredibly
human. Because this symbol wasn't mathematically
engineered in some pristine laboratory by scholars
trying to perfect a universal language. Not at
all. It was basically a happy accident born out
of human laziness. Well, laziness or, you know,
perhaps we should call it extreme efficiency.
Fair enough. Because if you look at historical
texts prior to the year 1425, There is absolutely
no known evidence of a special dedicated symbol
being used for percentages. So what did they
do? When people needed to express a fraction
of 100, they just wrote it out. They used the
Italian term pretento, which literally translates
to for 100. Just the full words. Yeah. Or if
they were in a rush, they would use abbreviations.
So you'd see things written out as per 100, P100,
or eccento. Which, I mean, that... Completely
makes sense if you think about the technology
of the time. You are writing with a quill. Parchment
and vellum are incredibly expensive. And every
drop of ink matters. You want to save space and
time wherever you can. Precisely. And we can
actually track the visual evolution of this shorthand,
which is so cool. There's this specific anonymous
arithmetic text from 1339. OK. And in this text,
you see the letter P. written with its descender,
you know, the long tail of the pea that hangs
down below the line. Yeah, yeah. It's crossed
by a horizontal or diagonal stroke. Wait, but
a pea with a line through the tail doesn't look
anything like the two circles in a slash that
we use today. That sounds more like a generic
proofreaders mark or something. Yeah, well that's
because it was just a standard abbreviation.
In medieval and Renaissance paleography, that
cross pea conventionally stood for words like
purr, pour, par, or pour. Ah, I got it. So it
was a generic shorthand, not a unique math symbol.
Exactly. The real breakthrough, like the moment
the percent sign, as we know it actually begins
to emerge, happens a little later. When was this?
So in a 1425 arithmetic text, well, specifically
in some pages that historians believe were added
around 1435, a scribe used the abbreviation PC.
Uh -huh. But they added a tiny little loop. or
circle floating right next to the sea. Wait,
what was the point of the little loop? Was it
just like a decorative flourish? No, not at all.
It actually served a highly specific grammatical
purpose. That tiny loop depicted the O ending
used in Italian ordinal numbers. Oh, like primo
or secundo? Exactly. Think of it exactly like
how we write the O at the end of the English
25th. It was a way of writing the concept of
percent O in this incredibly compressed, visually
distinct format. Oh, wow. So we essentially have
a P and a C with a little O floating around it.
I mean, this is basically a 15th century emoji.
Yes, that's a great way to look at it. It starts
out as full words, percento, then it gets abbreviated
to save time, exactly like modern texting, where
be right back becomes verb. And then over centuries,
it just morphs from letters into a purely visual
icon that doesn't even look like text anymore.
Right. What's fascinating here is that a rigid,
universally recognized mathematical symbol was
actually born from messy, hurried human handwriting.
It really is. Because the evolution didn't stop
with that Italian scribe. By the year 1650, that
PC with the little loop had evolved into a horizontal
fraction sign and it completely dropped the per
part. Wait, really? Yeah, it just became two
tiny circles separated by a horizontal line.
The letters had literally melted away into geometric
shapes. Wait, what about the slanted line? Because
I'm looking at my keyboard right now and the
line between the two circles is definitely slanted,
not horizontal. Right, so that slanted line is
called a solidus and it is a surprisingly recent
invention. Historians like D .E. Smith back in
1925 noted that the solidest form of the percent
sign is definitively modern. It took hundreds
of years for that horizontal line to tilt. It
is so strange to think about it that way. We
treat the percent sign like this ancient immutable
law of math, but it's really just the sloppy
handwriting of an Italian scribe that got passed
down and slowly distorted over centuries. It's
almost like a game of typographical telephone.
That's a perfect analogy. And that organic grassroots
evolution is exactly why the symbol has caused
so much friction in the modern era. Oh, the turf
wars. Yes, because it evolved naturally across
Europe. rather than being handed down by a central
authority with an instruction manual, it created
this massive global headache when it came to
printing it. Right, because once the printing
press arrives and eventually, you know, the typewriter,
things have to be standardized. Exactly. But
nobody could agree on what the standard should
actually be. It turns into an absolute typography
turf war. It really is a turf war. We have a
fractured global landscape today where different
languages and even different institutional style
guides within the same language completely disagree
on how to physically place the symbol next to
a number. I mean look at the conflict just within
the English language. Oh it's intense. On one
side you have the classic English style guides
like the Chicago Manual of Style and the APA
Manual. They explicitly prescribe writing the
percent sign following the number with absolutely
no space between them. So 50, then immediately
the percent sign. Right. But on the opposing
side, you have the international heavyweights,
the International System of Units, the SI, and
the ISO 310 standard. They strongly prescribe
placing a space between the number and the percent
sign. So 50. space percent. But why? I mean,
if everyone in the U .S. and the U .K. naturally
writes it without a space, why are the international
standards pushing for a gap? Well, because the
international standards treat the percent sign
in line with the general practice of using a
non -breaking space between any numerical value
and its corresponding unit of measurement. Oh,
I see. Yeah. Just like you would write 50 kilometers
with a space between the 50 and the kilometers,
they argue you must write 50 percent with the
space. OK, that makes sense. And they specifically
mandate a non -breaking space, which is basically
a piece of typographical glue. It tells the computer,
never put the 50 at the end of one line of text
and the percent sign at the beginning of the
next line. It keeps them visually bound together.
OK, I see the logic there. They want to treat
it like a scientific unit. But the rules get
even more complicated when you look at actual
text versus tables, right? Oh, yeah. If you are
writing for a newspaper, for instance, a lot
of style guides say you shouldn't even use the
symbol in running text. You should spell it out
entirely as the word percent and strictly reserve
the actual symbol for data tables and places
where physical space is severely restricted.
True. And if you think English is tangled, the
rules in other languages show just how localized
this symbol has become. Oh, do tell. Take Czech
and Slovak, for instance. In Slovak, you always
use a non -breaking space before the percent
sign. But in Czech, the spacing depends entirely
on the grammar of the sentence. Yes, if the number
is used as a noun, you put a space. But if it's
used as an adjective, like saying a 50 % increase,
Czech drops the space completely. That is incredibly
specific. The spacing changes based on the part
of speech. It does. And then you have Finnish,
where they always put a space. But if they need
to attach a case suffix, they actually glue it
to the percent sign. using a colon. Wait, they
glue it with a colon? Yeah, so an increase of
50 % visually looks like 50 space percent sign,
colon, n space, cosfu. Looks like a math equation
mixed with a typo. That is wild. It is. And the
placement of the symbol changes based on geography,
too. In Turkish, and some other Turkic languages,
the percent sign actually precedes the number,
not follows it with no space. And in Persian
texts, you might see the percent sign place either
before or after the number. I imagine directionality
also plays a massive role there. Like Arabic
is written from right to left, so the percent
sign naturally follows the number which places
it to the left of the digits. But Hebrew, which
is also written from right to left, actually
writes its numbers from left to right. So the
percent sign stays on the right side of the number
exactly like it does in English. It just highlights
how incredibly adaptable the symbol has to be
to fit into completely different writing systems.
But what really stands out in all these typography
rules is the human rebellion against them. Yes.
Oh, I love this part. If you are someone who
learns by watching how humans actually behave
rather than what rule books say, the percent
sign is the perfect case study. Look at the Dutch.
The Dutch are a great example. Their official
national rule says you must place a space between
the number and the sign. But most everyday people
completely ignore the rule and leave the space
out. Exactly. The same phenomenon happens in
North American Spanish. The real Academia Española,
the royal institution that oversees the Spanish
language, says the percent sign should be spaced.
Right. But in Mexico and the U .S., several style
guides and institutions just ignore Majid. They
follow local common usage and write it with no
space. So aren't these rigid typographic institutions
just fighting a losing battle against common
sense? I mean, if everyday people hate the space
so much that they refuse to use it, why do the
rule makers keep pushing it? Well, it's the classic
tension between prescriptivism, you know, how
things should be, and descriptivism, how things
actually are. Typography is fundamentally driven
by utility. The rule makers, like the ISO, prioritize
logical consistency. To them, treating the percent
sign exactly like a unit of measurement maintains
a neat, ordered system. Makes sense for them.
But human beings prioritize visual speed and
aesthetic convenience. A space before a percent
sign often just looks wrong to the modern eye.
It feels disconnected from the number it modifies.
So people simply discard the rule. human convenience
will always override institutional rules. We
vote with our keyboards. Exactly. And speaking
of keyboards, this tension over where to place
the symbol was ultimately hard -coded into our
lives when the typewriter forced the percent
sign into a permanent physical key. And once
it was trapped on that keyboard, a completely
different group of people decided to hijack it.
Right. Early computer programmers looked down
at their keyboards and saw a perfectly good,
highly recognizable character sitting right there
on the number five key. just waiting to be used.
Exactly. And because a percent sign is mathematically
meaningless to a computer's core binary logic,
it was essentially a blank canvas. Programmers
realized they could repurpose it for operations
that have absolutely nothing to do with fractions
of 100. And they gave it some amazing nicknames
along the way. Like, in hacker jargon, the percent
sign is sometimes called grapes, which, if you
look at the symbol, perfectly makes sense. Two
little round grapes hanging on a vine. That's
very visual, yeah. And in the programming language,
intercal, they humorously refer to it as 007.
Very fitting for a symbol with a secret identity.
Its roles in computing are vast, but let's look
at how it mechanically functions. In math and
logic, In programming languages derived from
C and B, the percent sign is used for the modulo
operation. Which is basically a fancy way of
saying find the remainder, right? Exactly. If
you divide 10 by 3, the answer is 3 with a remainder
of 1. So if you write 10 percent sign 3 in code,
the computer calculates the division, but only
hands you back that remainder, the 1. OK, got
it. It's a completely different mathematical
function than a percentage. Here's where it gets
really interesting. Because the percent sign
in computing isn't just doing math, it acts more
like a digital traffic cop. And its behavior
totally changes depending on what neighborhood
of the computer it's standing in. Oh, that is
a great way to conceptualize it. Let's look at
the web, for example. OK. If you look at a URI,
a web address, you will often see a percent sign
followed by a two -digit hexadecimal number.
This is called percent encoding. The Internet's
underlying architecture doesn't allow certain
characters like spaces in a web address. Right,
you never see a space in a URL. Exactly. So the
percent sign acts as a signal to the browser.
It says translate what comes next. A space becomes
percent sign 2 -0. It's a translation tool. Okay,
so in the web neighborhood, it's a translator.
But if we go over to the database neighborhood,
specifically SQL databases, it becomes a wild
card detective. Yes. If a database administrator
searches Lisa percent, the percent sign tells
the computer to fetch every single record where
the first name is Lisa, no matter what the last
name is. It's the traffic cop waving all the
cars through saying, yep, you start with Lisa.
Come on in. Lisa Smith, Lisa Jones, all of you.
That's exactly how it works. It also functions
as a visual tag, or a sigil. The sigil. Yeah,
like in a language like Perl, programmers use
a percent sign in front of a variable name to
indicate that the data is a hash, which is basically
a dictionary of key value pairs. Okay. By putting
the percent sign there, the programmer and the
computer instantly know what kind of data they
are looking at without having to read the whole
file. It's also used for formatting templates
in C, Python, and Ruby. or an ASP where a lesson
sign and a percent sign act as a start tag. And
even in command lines, right? Like in Windows
batch files, it represents parameters or environment
variables? Yep. Percent one, percent VAR one
percent. You even need two of them to print a
literal percent sign. But my absolute favorite
role it plays is the silencer. Oh, the comments.
Yes. In systems like Tex, Latex, PostScript,
and Matlab, If a programmer types a percent sign,
it tells the computer to completely stop reading.
Right. It creates what's called a line comment.
The machine reads the code, hits the percent
sign, and immediately ignores everything else
on that line. It's the traffic cop throwing up
a barricade. Stop right here, machine. The rest
of this line is for human eyes only. Basically,
yeah. Programmers use it to leave private notes
or instructions for themselves right in the middle
of the code, completely hidden from the computer's
execution. I mean, from a 15th century shorthand
for an Italian word to a symbol that literally
commands a computer to ignore data, that is an
incredible evolution. It really is. But the computer
scientists weren't the only ones to borrow the
percent sign. Linguistics took it, too. They
did. And they used it for a remarkably different
purpose. I mean, computer science drafted the
percent sign to communicate with rigid, perfectly
logical machines. But linguistics... borrowed
that exact same symbol to describe the beautiful,
messy, contradictory way that humans actually
speak. Exactly. In linguistics, if you place
a percent sign at the very start of an example
sentence, you are signaling that the sentence
is judged well -formed, meaning grammatically
correct by some speakers, but entirely ill -formed
by others. And this usually happens due to dialect
differences or even individual idiolectics. Remind
me, an idiolect is? An idiolect is the unique
fingerprint -like way a single specific person
uses language. So what sounds perfectly natural
to you might sound completely wrong to someone
from a different region or even just a different
neighborhood. So in linguistics, the percent
sign is essentially the symbol for we agree to
disagree. Essentially, yes. Which is so different
from the other linguistic markup symbols out
there. Like if a linguist puts an asterisk in
front of a string of words, that means it is
completely ill -formed. Just totally ungrammatical
nonsense across the board. A question mark means
the well -formedness is unclear. And my favorite,
the number sign, the hashtag, marks a string
that is syntactically fine, but semantically
nonsensical, like saying, the angry carpet ate
the sunset. Perfect grammar, absolutely no logical
meaning. But the percent sign sits in that ambiguous
middle ground. If we connect this to the bigger
picture, it is quite profound. How so? Well,
the percent sign represents relativity. In mathematics,
it always means relative to 100. But in linguistics,
it has evolved to mean relative to the speaker.
It has become the ultimate symbol of human context.
The ultimate symbol of context. Wow. And you
can see how deeply embedded it has become in
human context globally just by looking at how
Unicode handles it. Oh, absolutely. Unicode is
the international standard for encoding text
on computers, ensuring that a symbol typed in
Tokyo appears the exact same way in Toronto.
And they don't just have 1 % sign. The standard
is U plus 0, 0. But they also have a full width
percent sign and a small percent sign. They even
have a square Japanese percento character. What
does that look like? It takes the English word
percent. writes it in katakana, and squishes
it into one single square character to fit vertical
text layouts. Oh, that's brilliant. And let's
not forget the Arabic percent sign. Because Eastern
Arabic numerals use a dot to represent a zero,
their percent sign adapts perfectly to that reality.
It replaces the two little circles of our standard
symbol with square dots set on edge to match
their numbers. The symbol physically adapts to
whatever culture it finds itself in. It truly
is a typographical chameleon. It really is. We've
covered some serious ground today. Let's trace
the path of the journey you just went on. We
started with a lazy 15th century Italian scribe
rushing to write percento to save expensive parchment,
throwing a tiny little cursive O loop onto his
Pisa. We watched that messy shorthand morph into
a rigid mathematical symbol that sparked international
typography wars between Chicago style guides
and European standard bearers. Then we saw it
locked onto the typewriter. only to be hijacked
by early computer programmers. It became the
grapes of hacker jargon, acting as a digital
traffic cop, translating web addresses, waving
through SQL databases, and throwing up barricades
to silence lines of MATLAB code. Before finally
being claimed by linguists as a marker for the
messy relative nature of human dialects, I told
you at the beginning of this deep dive that you'd
never look at your keyboard the same way again.
The next time you reach up to hit the number
five key to write 100%, I want you to realize
that you are invoking centuries of human history,
typographical rebellions, and overlapping digital
dimensions, all in a single keystroke. It is
a massive amount of historical weight for one
little key to carry. So what does this all mean?
We know that this mighty, globally recognized
fundamental mathematical symbol evolved purely
from an Italian scribe's hasty handwritten abbreviation.
It makes you wonder, what messy internet -era
text message shorthand or emoji are we using
on our phones right now, today, that will somehow
become a rigid, fundamental mathematical or coding
symbol 600 years in the future? Will the laughing,
crying face be the symbol for a new kind of quantum
variable? We'll leave you to mull that one over
the next time you look down at your keyboard.
Keep questioning the everyday things around you
and keep exploring.