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Understand the types of numbers JavaScript can work with; how to store numbers in variables; and why numbers in web forms aren't really numbers.

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[MUSIC]

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In the last stage, I talked about strings.

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A string is a series of letters, numbers and

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other characters enclosed in quote marks.

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Strings are one type of data you'll work with in JavaScript.

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Another type of information you'll encounter frequently is a number.

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You use numbers to perform calculations,

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like determining the total cost of items in a shopping cart.

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Or adding points to a player's score in a game.

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Or keeping track of the number of seconds passed since the visitor

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performed a certain action.

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In JavaScript, numbers can be whole numbers called integers,

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like [SOUND] five, zero, negative 100, 9,999.

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Or numbers with decimal points to represent fractions of a whole number,

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like 3.14 or negative 9.88888 or 0.0000009.

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Numbers like these with decimal points are also called floating point numbers.

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JavaScript even lets you use scientific notation to represent really large or

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really small numbers.

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Just [SOUND] as with string values, you can put a number in a variable or

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assign a number to a variable using the equal sign.

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[SOUND] Unlike strings, however, you don't put quote marks around a number.

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If you do, then you have a string, not a number.

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This is a confusing part of working with strings and numbers.

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So in this line of code,

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the value stored in the variable aString isn't the number 10.

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It's a string made up of the character 1 followed by 0.

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This [SOUND] can lead to some weird and

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confusing behavior, like making some math operations not work as expected.

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We'll look at how to convert a string containing a number into

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an actual number in a later video in this stage.

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But just keep this in mind, a number inside quotes isn't really a number.
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