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To look at some of the Python operators
that we can use with numbers,

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We're going to continue with our Hello World project.

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So we want to create a new file here. We'll call this one operators.

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So what I'll do, is start by binding a couple of labels to two int values.

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Remember that you'll also hear that described as assigning the values to the variables,

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but that's not the best way of thinking about it in Python.

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So I'm going to type a = 12, and on the next line, b = 3.

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Whenever we use the name a, Python
knows that it refers to the value 12.

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Similarly, b will refer to the value 3.

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So let's create some expressions to see the basic Python arithmetic operators.

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So I'll start on line 4, print parentheses, and then within the parentheses, a + b.

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Next line, print parentheses again, this time a - b,

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and what I'll do is, actually, go back up to the previous line.

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I'll do a tab and I'll just put the expected results there. So 15 would be the value of the first one, the next one, 9.

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Alright line 6, parentheses after the keyword print, a * b,  and the value for that should be 36.

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Next line, print parentheses and then a / b,

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and that should give us the value 4.0.

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Next line, print, then in parentheses a integer division, which is two forward slashes with b,

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and that should give us the value of 4, and again it's integer division,

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and it's rounded down towards minus infinity.

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And the last line we'll do a, be consistent here with the formatting, a percent b, which is the remainder operator.

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and that's going to 0 modulo and it's the remainder

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after integer division.

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Alright, I'll just fix this line up as well, just so it's consistently spaced.

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Alright and there we have it.

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So probably, there shouldn't be any real surprises here,

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except possibly the use of an asterisk for multiplication, if you're new to programming languages.

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x is a valid name for a variable, which means we have to use the asterisk for multiplication.

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So just run the program first, to make sure we get the expected results,

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and you saw me add those as comments, in the, or for, each line. So we'll run it,

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and there's our results, as you can see, exactly as we've got written in the comments.

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Note though that although we're using int values,

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division produces a float result, 4.0, which you can see in the source code on line 7.

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Now if we use two forward slashes to perform integer division, then the result is an integer.

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You saw that on line 8 and we got the expected result 4, in this case.

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So that can be important if we intend to use that value in a place where an int must be used.

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So to give the example, I'm going to add some code to print a blank line, then the numbers 1 to 3.

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Now don't worry too much about understanding this next bit of code.

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I'll use one here to illustrate the point, but we're going to be discussing for loops in detail, in the next section in this course.

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For now, just make sure that you put 4 spaces before the word print,

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and a colon at the end of the for line, and you'll see what that means when I start typing now.

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Alright, so here I am now on line 11. I'm going to add print, and an empty parenthesis to print an empty line,

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or blank line, and then next I'm going to type for on line 13, for i in range, and parenthesis, 1, 4

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in the parenthesis, and then colon immediately after that.

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Now if I just press Enter, you can see that IntelliJ has tabbed that for us, but if that's not happened for you automatically,

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you'll need to put those four spaces in, as I mentioned.

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So print and parentheses, the letter i, and
if I run this, you can see we get the results 1 to 3.

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Now the values we used in range, and I'll just close down the run window now,

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there on line 13, must be integers.

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So if I change this to use a / b, come down here, so instead of 4, changing that to a / b,

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we get an error there, or we will get an error when we run it.

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As you can see, we've got a type error there: float object cannot be interpreted as an int

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So performing integer division, using two forward slashes instead of one, would actually prevent this problem,

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and you can see we get the numbers 1 2 3 and the warning has now disappeared.

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So essentially, we change the code to perform integer division and the result of a // b, two foreward slash b,

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is now an int.

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We'll see another way to cope with situations like this, but for now it's something you need to be aware of.

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Python is strongly typed, and you can't use a float in places where an int must be used.

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Alright, so code like a + b, as I've done up here on line 4, is called an expression.

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In the next video, we'll learn what expressions are.

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See you in the next video.