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Every programming language allows you to perform basic math like addition, subtraction, division and multiplication. These are called binary operators.
Further Reading

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[SOUND] Every programming language allows you to perform basic math like addition,

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subtraction, division and multiplication.

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These are called, binary operators.

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They called binary operators, because they have numbers on either side.

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These numbers are called operands and

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the symbol in the middle is called the operator.

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Let's list out all the operators in Swift.

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[SOUND] You have addition, [SOUND] subtraction, [SOUND] division,

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[SOUND] multiplication and remainder.

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[SOUND] The last one,

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might be a bit misleading because the operator is a percentage sign.

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However, it doesn't give you the percentage, it gives you the remainder,

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when dividing two numbers.

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In the above example, 11 divided by five gives us a remainder of one.

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Or another way of seeing it, is that we can fit two fives, with an 11 and

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one remains, so let's take a look at how we can use these operators in our code.

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So, going into Xcode, we'll go up to the file menu, select New playground.

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We'll call this playground operators, leave platform as iOS,

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hit Next and then hit Create.

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All right, once again deleting the var STR [SOUND] because we don't need that.

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So the first thing we'll look at, is the edition.

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Now, if you've ever done any algebra, you've probably used x.

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You know, you've always, like, had to find out what is x.

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So let's say var x = 1 + 2.

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And in the results pane you will see that the value is 3.

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Now of course since it's a variable we can name it anything we want,

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we don't have to call it an x.

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So, let's take a real world example, so I'm gonna delete this line.

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And let's say we have the height [SOUND] and width of a room.

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So I'll say height [SOUND] is equal to 12 [SOUND] and width is equal to ten.

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So, I'm assuming that this height and width are in feet.

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[SOUND] Now, you're also probably wondering why these are constants.

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Well they're constants because the height and width of a room don't exactly change.

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So, let's figure out the area of that room.

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So I'll say, let area equal, so we have to multiply the height times width.

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[SOUND] So I'll say height,

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[SOUND] the multiplication sign is an asterisk [SOUND], times width.

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[SOUND] And, this will give us the area of the room.

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Of course, the area will be in feet.

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Once again I've used the key word let, which creates a constant.

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And, all of these are constants because we're assuming the height and

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width of a room don't change, well, unless you knock down a wall or something.

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But, we're not gonna get into that mess.

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So let's say we want to convert the area into square meters because, most of

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the world uses the metric system, except the United States, because we're special.

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So we're gonna say, let area in meters [SOUND] equal area divided by something.

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So that's the division sign, this forward slash over here.

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So how do we find out what is the area in square meters?

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So one square [SOUND], meter is equal

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to one square foot divided by 10.764.

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So I already have my area in feet.

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So all I have to do is divide this by 10.764.

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[SOUND] And this will give me the area in meters.

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Now you'll notice that in the results pane on the right, it gives me a number which

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is a whole number, so this is exactly 12 meters or 12 square meters rather.

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That can't be right because when you divide a number by a fraction,

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you should get a number with some decimal places.

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So something is going on here.

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Swift is making some assumptions on our part.

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And it's assuming that, if our area, the number that we're dividing by,

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is an integer, then the results,

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which is this area in meters, will also be an integer.

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And we don't want it to be an integer.

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So one way of converting this, is, we can go back here and

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make sure that both our height and width are doubles.

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So all we have to do is put a .0 on to this, .0.

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So now you'll see that the number on the results pane is a big decimal number.

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That's one way of doing it.

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But what if we are writing a program and

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we didn't have the ability to change the original constants?

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We didn't, we couldn't change the fact that the height and width were doubles.

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So we can go here.

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Let's, let's just go back and make these integers.

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So there's a way that we can convert our existing number in to a double.

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So we can convert this area in to a double.

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So just like we used the print function and we passed it.

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A variable, we can use double,

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[SOUND] the type double [SOUND] and pass it a variable.

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And what it'll do is, it'll convert that variable or

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that constant from that particular type into a double.

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Granted of course that, you know that has to be a float or

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an integer you can't pass it a string and expect it, to create a double unless it

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is a valid number but if you had like a string flow world,

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it would make no sense to convert that into a double.

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And that's one way we can convert a constant into the type that we want.

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So now area in meters is a type double and it has decimal places and,

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this would matter for accuracy, cuz if you're writing a program that requires you

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to calculate stuff in you know, have all these different calculations,

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you have to make sure that you provide accuracy to your user.

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We've looked at multiplication, addition, and division.

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Let's look at the remainder function, or the, the remainder operator.

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So let's assume that we have chairs.

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So let me create a constant.

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I'll call this chair width.

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[SOUND] And I'll give it, let's say it's three feet, right?

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So we have chairs and we wanna line,

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we wanna see how many chairs we can line up against a wall, or against the wall

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that we have already which is the width of this wall is ten feet.

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All right. So,

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how many chairs can I safely line up against that wall?

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I mean, if you just did basic calculation you would see that you

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can fit three chairs.

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But, let's say we need to figure this out programatically.

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So I'll create another constant called space remaining [SOUND] and

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what I can do is, I can take the width and

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use the remainder operator and provide it with the chair width.

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So essentially I'm taking the width of the wall using the remainder operator, and

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then using the chair width.

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And, what this will give me is how much space is

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remaining in the wall after I have accommodated, x amount of chairs.

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So, to calculate the number of chairs [SOUND] I

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can do width divided by chair width.

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[SOUND] So this will give me the number of chairs I can fit on that wall,

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and the space is remaining for

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other decoration on that wall, whatever you wanna put.

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This is of course an example that I've created, but

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the remainder operator actually has a lot of used cases which you will find.

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You know, for example, you can always divide a number by two and

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if the remainder is zero you know it's an even number.

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So that's one way of calculating even numbers, or calculating odd numbers, for

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that matter.

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So there you have it.

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Here are all the basic operators that you'll be using when,

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you know, performing all kinds of math calculations.

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Now, one thing happens is that when you have multiple operators on the same line.

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There's a precedence on how these operators get executed.

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And that's exactly what we'll cover in our next video.
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