# 2.8 Numbers (Deep-Dive) - IP

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>> Hello everyone. Welcome back to Intro to

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Python here on Cybrary On Demand.

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I'm your instructor Joe Perry.

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In this video, in this lesson Lesson 7,

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we're going to be talking all about Python numbers.

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Numbers in Python, we've used a bunch of them so far,

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we've done a bunch of logic with them,

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but I just want to take

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a few minutes here in this lesson,

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and just break down all the

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different components of them,

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so that we can understand

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them a little bit more effectively.

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Before I jump to the VM,

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I'm jumping in them a little bit.

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Our objectives in this video,

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we're going to learn about the different

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math operations in Python,

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we're going to learn about the differences

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between ints and floats,

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and how to use each of those.

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That's really all we're going to need to

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worry about for numbers in Python.

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So much of the hard work of

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numbers is abstracted away from us,

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so we don't have to worry about them.

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They do have methods much like strings do,

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but for the sake of an introductory course,

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we're not really going to be worried about those.

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The math operations in Python are just like

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math operations in math.

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We could do things like 4 plus 2,

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5 minus 4, or we'll do 10 times 8,

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and as a little example right here,

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20 divided by 5.

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Now, you'll notice this is different,

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and I've alluded to it in previous videos.

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That printed 4.0 There is a difference,

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and the difference that I mentioned right here,

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in this objective, between ints and floats.

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In Python, all of these things are numbers.

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In Python, we'll use it and make it work just fine.

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But it is worth noting that there is something under

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the hood being abstracted away from you that

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can be useful and can be important.

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When you're doing division,

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if you don't want to get back in decimal place,

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you'll do what's called floor division,

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which is going to just divide and just give

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you the round number of that division.

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Remember from our use of modulo, in a previous video,

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that if we did 20 modulo 5,

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it'll give us the remainder,

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which in this case, of course, is 0.

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21 modulo 5 would be 1.

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If we did 21 modular 5 and 21 floor divided by 5,

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we'll see that 4,

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even though 21 isn't evenly divisible by 5,

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4 is the dividend,

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and 1 is the remainder.

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I think I'm using that word. I think

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it's dividend, that might be divisor.

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I haven't actually had to use the names for

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our arithmetic in like 20 years or so [LAUGHTER].

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But so that's the basic way of

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using ints and floats,

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and that's the difference between them.

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The primary thing to understand about floats

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is that floats have decimal places.

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Floats can address non-whole integers.

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Integers are whole numbers.

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They can be negative or positive.

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They're just never going to be

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fractional numbers whereas floats

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can address fractional numbers.

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I showed you, we have plus,

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minus, times, divide.

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We also have exponentiation available to us.

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4 to the power of 4 is going to be 256.

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Then we have one more subject and numbers.

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Numbers is a much easier lesser than strings.

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One more subject to numbers it's really cool to address.

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There's a special number in Python.

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That's not really a number, so

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it is a placeholder for a number.

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That's the underscore. You can see here that,

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now underscore equals 256,

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because it is the result of

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the last mathematical operation.

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If we did 5 plus 3,

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and print the underscore, it'll be 8.

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Underscore is just a useful way

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to track math, and we can do,

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I'll show you in just a second one or

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the other really cool things we can do with it,

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but I do want to point out,

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never ever do that.

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Never assign a value explicitly to underscore.

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Because what will actually happen there is,

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you'll create a new variable and you're going to

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blow away the built-in magical underscore,

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so never ever do that.

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But one of the other things you could do with underscore,

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with the pseudo number that is underscore,

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is you can use it in loops.

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For underscore in range 10, print, hello.

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What's cool about this is, what it's

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really doing is, it's just saying,

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for each number in this range,

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without ever actually storing that number anywhere,

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it's just a useful shorthand in Python where you're

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just trying to use that range to just to

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count the number of times you're doing something,

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and the number itself isn't relevant.

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It's actually all there really is

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to math operations in Python.

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You do them the same way you would do in algebra.

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If you have to use an order of operations,

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it works exactly the same way it does in math.

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Then we talked about the differences

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between integers and floats.

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The idea that floats can use fractional numbers.

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That's all there is to Lesson 7.

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It's a palate cleanser between strings and the,

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well, much more interesting and somewhat more

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challenging lists and dictionaries that are coming up.

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Speaking of which, I hope to

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see you back in our next lesson,

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Lesson 8, we're going to do a deep dive on lists.

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Of course, all of the material for Lessons 5 through 9,

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we have a Lab 4,

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provided by the Spectacular Company Next Tech.

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I know that I keep talking about them.

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I actually should probably address

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they are a partner of Cybrary,

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but they're not actually sponsoring

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this video in any way.

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I'm not being paid to

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talk about them or anything like that,

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we just use their lab,

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and absolutely, I just love it so very much,

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and I want all of you to use it as well.

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Please, by all means, take some time,

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do those exercises, and really dig into the code.

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I'll see you back for Lesson 8.

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Thank you as always for watching.

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I'm your instructor Joe Perry,

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and you've been watching Intro to Python here

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on Cybrary On Demand.

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