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Hey and welcome.

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This lesson is all about JavaScript math, and we can have a lot of fun with math.

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And of course, math is super useful when you're coding JavaScript, especially in generating random

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numbers, rounding up, rounding down and rounding numbers in general.

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So used quite a bit, especially when you're creating games or any type of interaction.

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Random is a great way to go to create some type of unexpected result for the user.

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So we've got math floor math sealing.

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The difference is that the math floor returns the largest integer less than or equal to a given number.

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So what we've got some examples at the Mozilla developer network.

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So if you've got five point ninety five five point zero five Barthe four five or Amarth floor negative

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five four point zero five.

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So what do you think the answer for the first three is?

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And if you said five, you are right because they're all rounding down to the nearest value as opposed

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to ceiling, which does the opposite and rounds to the returns, the smallest integer greater than or

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equal to give a number.

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So what it's doing is that it's rounding it up.

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So ceiling dot, negative dot 95 is one because it's rounding it up to one.

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Ceiling four is going to be four because that's the closest that's the rounded value up ceiling, seven

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point zero zero four or zero zero zero zero four.

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So anything above seven is going around to eight and opposite.

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If we're doing negatives, you see that it returns to the negative number.

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So it's not rounding it up as per say, it's rounding it back down to the nearest numbers are going

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down.

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That's the difference between the negatives there.

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And when you run it, you can see that we get the results one four, eight and negative seven.

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And then my favorite Amarth random use it all the time is gives you the ability to generate a random

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value floating point, pseudo random number between zero and one.

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So what that means is when you do math random, you get a random value, zero dot zero Derat and a bunch

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of digits after that.

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So that's what this is doing, zero to one.

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And also keep in mind as well, inclusive of zero, but not one.

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So that's why when we are trying to get math random, we use math flaw in order to find two and what's

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being returned back.

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So random integer.

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So the maximum value that we want to receive and we're using my floor to round it down as well as math

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floor for the maximum value.

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And then we're multiplying that by math random.

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So what happens here is in this case, when we use this function, we get value or passing in three

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and the math floor is going to be three as well.

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And we're multiplying it by math, random, and then we're multiplying it by floor again.

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So that way we're getting a value of zero one or two.

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And that's why three is never included, because we're not not one when we're rounding it.

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Also, if you want to round it up.

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So if you want to get one, two or three, in this case, you could use math ceiling.

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But most commonly people use math floor and round it down.

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And if you want it to have a number of one, two or three, you would just add one to it.

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So you see that as well within a lot of expressions.

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And then we just have the basic math, random output.

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So number between zero and one.

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So we notice all of the decimal places.

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So they're all zero decimal and a bunch of digits after that for math random.

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And of course, there is a challenge at the end of this lesson, and that is to create a function that

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can generate a random number.

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So getting to inputs where we've got a minimum and a maximum value and then returning back a random

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value depending on what is input into the function.

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So maximum is exclusive and minimum is inclusive.

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So keep that in mind.

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Generate this function and I'll walk you through it so you can pause the video here and I'll walk you

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through the solution.

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Let's open up the ED and we're going to just create our function.

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You can call this get random.

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It's going to be expecting two parameters.

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So minimum and a maximum value to be passed in for the minimum value.

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So we're going to take whatever is passed in using math ceiling.

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We're going to take that minimum number and we're going to use math ceiling in order to generate the

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minimum number and then maximum number.

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If we're going to do the same thing, we're going to apply my floor to that maximum number and then

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returning a back math floor math random and then multiplying it by maximum, subtracting the minimum

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and then adding the minimum amount back into the formula.

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So refresh we can in values now into that function where we've got a minimum return value, a maximum

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of four, as you can see that now it's generating a random number all the time different.

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And the minimum that it's going to be is one.

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And the maximum that we're going to return back is going to be three.

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So it's never going to hit at four.

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And you can use this formula in a number of ways.

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So if you want to get a random value from one to five, you can see that now it's returning back for

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if you update that and bring it down to two.

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So you're always going to get a random value anywhere from one to two, not including the two, because

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remember, that was part of it's exclusive of the maximum value.

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So it's always returning back one in this case.

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So go ahead and try the.