Numbers

Quick reference

• 00:04 In this video, we're going to look at number data types.
• 00:06 And I mentioned earlier when we talked about the different data types that
• 00:10 numbers are a data type.
• 00:11 And that's not precisely true, a number is a number, but
• 00:15 numbers in Python get broken up into different things.
• 00:18 There are floats, there are integers, there are several others as well.
• 00:21 We're just going to look at floats and integers in this video.
• 00:24 And in fact, in this course, these are the two main ones.
• 00:27 So let's create a variable, we'll call it num_1, and set it equal to 10.
• 00:31 And let's do another one called num_2, and set it equal to 3.
• 00:36 Now we learned in the last video all about math,
• 00:41 so we can go print (num_1 / num_2).
• 00:46 And if we save this and run it, we get 3.
• 00:48 Well, that's not really true, is it?
• 00:50 If I pull up my handy-dandy calculator here and if I go 10 divided by 3,
• 00:55 I see the answer is 3.3333333.
• 00:58 Python is trying to tell us that the answer is 3.
• 01:00 So what's going on here?
• 01:02 Well, we're using whole numbers or integers, right?
• 01:05 And an integer can be positive or negative, it could be -10,
• 01:08 that's still an integer, but they're whole numbers.
• 01:11 And when you use whole numbers like this, Python treats them like whole numbers and
• 01:15 it round up or rounds down.
• 01:17 So that's why we're getting the answer 3, because Python says, okay, you want to
• 01:21 use integers, I'll return an integer and an integer is a whole number 3.
• 01:25 Now, sometimes that's what you want, sometimes you want precision,
• 01:28 you want the actual decimal point answers.
• 01:30 Especially if you're building a shopping cart,
• 01:32 somebody's buying something from you, it's $19.95.
• 01:35 You don't want to just round it up to 20,
• 01:37 you want to be able to handle those decimal points.
• 01:39 And for that, we use something called floats.
• 01:42 They're floating point numbers, and it just means decimal, basically.
• 01:45 So if we go 10.0 divided by 3.0,
• 01:49 now Python goes okay, you're using floats, I can return a more precise answer.
• 01:54 So if we save this, run it, we get 3.33333,
• 01:57 which is pretty much what our nice handy dandy calculator showed us.
• 02:02 So it's important that you pick which one you need to use.
• 02:06 So if you need decimals, you're definitely going to want to use decimals
• 02:09 in your coding, right, because Python can't guess this stuff.
• 02:12 You have to be very specific.
• 02:13 You have to tell it otherwise, if you're just using whole numbers, these integers,
• 02:18 it's going to return an integer answer.
• 02:20 And sometimes that's fine, sometimes you don't want that.
• 02:23 So one kind of interesting thing, if we use a float, 10.0, and
• 02:27 right here I'm just going to write decimals.
• 02:30 Here I'm going to put whole numbers, int, it stands for integers.
• 02:36 So anyway, 10.0 and 3, what do you think's going to happen here?
• 02:40 If you run this, again we get 3.333.
• 02:43 You only have to use the float for one of these things, and
• 02:47 then Python figures out okay, they want to use floats.
• 02:51 So we could switch it around even, still going to get 3.333.
• 02:55 That's kind of interesting.
• 02:56 So those are the number data types, pretty straightforward.
• 02:59 I've mentioned in an earlier video, when you're dealing with variables and numbers,
• 03:03 you don't ever want to wrap your numbers in quotation marks,
• 03:07 because this is no longer a number.
• 03:08 Now this is a string, because anything wrapped in quotation marks is a string.
• 03:12 And if we try and save this and run it,
• 03:14 we're going to get an error because you can see, it's string and integer.
• 03:18 You can't take the word 10 divided by the number 3,
• 03:22 it just confuses the heck out of Python.
• 03:24 So be sure and be consistent and never use quotation marks whenever you're
• 03:29 dealing with numbers, unless you want it to be, if you have a string and
• 03:33 it's like, my favorite number is 10.
• 03:36 And obviously you can use a number inside here, but
• 03:39 you can't do math with this obviously.
• 03:41 So in the next video, we're going to look at assignment operators.

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