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JavaScript provides a library of constants and functions that are useful when doing mathematical operations in JavaScript. These items are stored in an object named Math, and in this video we will take a look at several of these functions.

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[? Music playing ?] [Treehouse]

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JavaScript provides us with a wide variety of functions

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and constants that are useful when doing math.

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These are stored in the Math Object, so let's take a look.

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So we've seen the different ways of creating numbers and comparing numbers,

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but there are a few more things that we would want to do

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with numbers that aren't able to be done with just the simple operations that we have here.

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For instance, rounding numbers, getting random numbers, doing square roots, or powers,

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or, for instance, maybe operations like sine and cosine,

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the trigonomic functions that we would want to use

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for instance if we're doing some sort of geometry.

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Fortunately, JavaScript provides an object called Math,

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and that's Math with a capital M.

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And there are different properties and methods on this that relate to common mathematical operations.

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Let's say we want to create a random number.

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So we can create a variable called U,

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and to create a random number, we use our Math Object.

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So, that's capital Math,

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and then there are either properties or methods that we want to call on it.

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To get a random number, we want to do the random method.

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So do Math.random, and then use parentheses to call it.

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So if we refresh, go to our page, and we evaluate U,

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which is the number we just assigned to Math.random's value,

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we'll see we get a number 0.407 blah blah blah,

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and this is because Math.random returns a value between 0 and 1.

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Now this may not be exactly what you want.

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You may have been wanting a number 0 through 10.

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Well, here's how we can do that.

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Because Math.random will return a value between 0 and 1,

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the upper bounds is obviously 1,

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but if we wanted a number 0 through 10, our upper bounds for that range would be 10.

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So an easy way of doing that would be multiplying it by 10.

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So now if we refresh, we should now get a number between 0 and 10.

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We get 9.2.

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Again, every time we refresh it, we're going to get a different number

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because random, every time it is called, will give us a different number.

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So if we keep saving and refreshing, we should get, hopefully, numbers between 0 and 10.

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Now, obviously the numbers that we get here are between 0 and 10,

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but they're not whole numbers.

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So what could we do? Well we could round them.

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So let's take this whole expression here, our Math.random times 10,

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and let's call another method that's on the Math Object called round.

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So what round will do is it will take a number and round it to the nearest whole number.

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So, again, what this will do is it will round it to the nearest number.

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So now we get 1, in this case, but we should always get a whole number between 0 and 10.

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So let's take a look at what round does.

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So if we take a variable V and do Math.round(2.3), V should be 2,

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and if we do 2.7, round should round up to 3.

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And then if we do 2.5, it will round up to 3 as well.

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So Math will round up from .5 and down for anything below .5.

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Now, what if you always want to round down?

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We can do Math.floor,

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and if we put in 3.7, W should always be 3.

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So it will always round down.

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If we want to do the opposite and always round up, we'll use Math.ceil.

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And that's ceil, which is short for ceiling.

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And if we did, for instance, 6.2, Math.ceil of 6.2 would be 7.

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Now there are a couple of other methods.

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For instance, if you wanted to take the power of something, we could do var Y = Math.pow,

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and this takes 2 arguments, the base and the exponent.

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So if you wanted to take 2 to the power of 5, we'll do Math.pow(2,5).

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And Y would be 32.

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And we also have the square root method.

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So we'll take Z=Math.sqrt for square root.

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So this just takes 1 argument. So say the square root of 4. Z should be 2.

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And this will work for things that won't square root so easily like 5.

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You get 2.2, or for instance, the square root of 2 will 1.414.

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Now there are quite a few different things in the Math Object

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that you may want to use at certain points in your programs.

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You'll know them when you need them, for instance, sine or cosine.

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But we can take a look at what our options are just by typing in Math into the console here

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and expanding it out.

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You can see we have things like floor, ceil, rand, pow,

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things like min and max, which are nice.

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For instance, if we take Math.min and pass in 2 and 4, it will return us the minimum,

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and similarly maximum will return the maximum.

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And you can add as many arguments as you like to Math.min or max.

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So anytime you need the min or max, you can get those.

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Sine, cosine, and tangent are available in sine, cos, and tan.

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As well as arc sine, arc tan, and arc cos in acos, asine, and atan.

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Again, depending on what you need to do, you may never use these,

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but if you're doing some interesting geometry, obviously these will come in handy.

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Also, we have abs, which will return the absolute value.

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So, Math.abs of 1 would be 1.

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Finally, you'll see up here we have some things that aren't methods,

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but instead they are constants or simply properties of the Math Object.

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So if you need a pretty decent value of pi, you can do Math.pi.

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So Math.pi, which is 3.14159 down a few decimal places.

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Or if you need e or if you need the natural log of 10 or the value of e or the square root of 2,

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these are all constants that are stored in the Math Object.

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Anytime you need to refer to it, I recommend just taking a look at Math in your console,

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and it will give you the list of constants and functions

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that will be commonly used in mathematical operations.

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[? Music playing ?] So now you should be familiar with all the tools you'll need

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to use when doing math in JavaScript.

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