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• In the 16th century, the mathematician Robert Recorde

• wrote a book called "The Whetstone of Witte"

• to teach English students algebra.

• But he was getting tired of writing the words "is equal to" over and over.

• His solution?

• He replaced those words with two parallel horizontal line segments

• because the way he saw it, no two things can be more equal.

• Could he have used four line segments instead of two?

• Of course.

• Could he have used vertical line segments?

• In fact, some people did.

• There's no reason why the equals sign had to look the way it does today.

• At some point, it just caught on, sort of like a meme.

• More and more mathematicians began to use it,

• and eventually, it became a standard symbol for equality.

• Math is full of symbols.

• Lines,

• dots,

• arrows,

• English letters,

• Greek letters,

• superscripts,

• subscripts.

• It can look like an illegible jumble.

• It's normal to find this wealth of symbols a little intimidating

• and to wonder where they all came from.

• Sometimes, as Recorde himself noted about his equals sign,

• there's an apt conformity between the symbol and what it represents.

• Another example of that is the plus sign for addition,

• which originated from a condensing of the Latin word et meaning and.

• Sometimes, however, the choice of symbol is more arbitrary,

• such as when a mathematician named Christian Kramp

• introduced the exclamation mark for factorials

• just because he needed a shorthand for expressions like this.

• In fact, all of these symbols were invented or adopted

• by mathematicians who wanted to avoid repeating themselves

• or having to use a lot of words to write out mathematical ideas.

• Many of the symbols used in mathematics are letters,

• usually from the Latin alphabet or Greek.

• Characters are often found representing quantities that are unknown,

• and the relationships between variables.

• They also stand in for specific numbers that show up frequently

• but would be cumbersome or impossible to fully write out in decimal form.

• Sets of numbers and whole equations can be represented with letters, too.

• Other symbols are used to represent operations.

• Some of these are especially valuable as shorthand

• because they condense repeated operations into a single expression.

• The repeated addition of the same number is abbreviated with a multiplication sign

• so it doesn't take up more space than it has to.

• A number multiplied by itself is indicated with an exponent

• that tells you how many times to repeat the operation.

• And a long string of sequential terms added together

• is collapsed into a capital sigma.

• These symbols shorten lengthy calculations to smaller terms

• that are much easier to manipulate.

• Symbols can also provide succinct instructions

• about how to perform calculations.

• Consider the following set of operations on a number.

• Take some number that you're thinking of,

• multiply it by two,

• subtract one from the result,

• multiply the result of that by itself,

• divide the result of that by three,

• and then add one to get the final output.

• Without our symbols and conventions, we'd be faced with this block of text.

• With them, we have a compact, elegant expression.

• Sometimes, as with equals,

• these symbols communicate meaning through form.

• Many, however, are arbitrary.

• Understanding them is a matter of memorizing what they mean

• and applying them in different contexts until they stick, as with any language.

• If we were to encounter an alien civilization,

• they'd probably have a totally different set of symbols.

• But if they think anything like us, they'd probably have symbols.

• And their symbols may even correspond directly to ours.

• They'd have their own multiplication sign,

• symbol for pi,

• and, of course, equals.

In the 16th century, the mathematician Robert Recorde

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B1 US TED-Ed symbol sign shorthand mathematician multiplication

# 【TED-Ed】Where do math symbols come from? - John David Walters

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osmend posted on 2017/11/04
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