Original subtitles

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Hi again, in this lecture I'll show you

how to do math operations with numbers.

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So we're going to look at math operators.

Let's go straight away and open a Python

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section and let me write a math

expression there. 20 minus 10 divided by

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5 times 3 in the power of 2 and what we

get is 2.0. So why did I write this a

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long expression? Well because I want to

explain to you the order of operators so

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when you have multiple operators in an

expression the one to be executed

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first is the exponent, so we have 3 in

power of 2 here that will give us 9.

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So power is the first to be executed and

also that is division and multiplication.

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Actually division and

multiplication are on the same level.

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We're talking about order but the one

that is first will be executed first so in

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this case division is the first one so

what will happen here is Python will

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ignore minus for now,

so it will divide 10 by 5 and it will

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give 2 then it will do 2 times 9.

So again 10 divided by 5, 2 times 9, 19.

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And then we have the rest of the operators

which could be a plus or minus so in

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this case we have minus so 20 minus 18.

We have 2.0. You'd ask why we have 2.0?

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Because 10 divided by 5 gives 2.0.

So division outputs a float in Python 3.

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If you are on Python 2, it would output

an integer. Now to make your expressions

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look better, you'd want to remove the

spaces for the power operator and also

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you do like that somehow you can read it

better,

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so 2 times 9 and then 20 minus 18 and so on.

You get the idea.

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You get 2.0 again and now if you want to

execute the minus operator first

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you'd want to put that inside brackets.

So why did we get 18? Well because 20

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minus 10 gives 10 and then 10 divided by

5 gives 2 and then 2 times 9 gives 18.

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That's the idea. And then you could also do

this, put these in brackets and what

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would happen here is you know 10 here,

15 here in the power of 2, so 15 in the

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power of 2, and then 10, so 10 divided by

15 in the power of 2. Let's see what we get.

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Yeah we got that, so let's see if I was

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Right.

15 in the power of 2 we get 225.

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And then we got 10 on the other side, so 10

divided by 225. We get that number.

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So whenever you want to change the

order of operators, you should use

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brackets and so I hope you get the idea

and please try this out, so try to do a

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few operations with numbers to get used to it.

And yeah, I'll talk to you later.

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Thanks.