Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:00,269 --> 00:00:04,680 Hi again, in this lecture I'll show you how to do math operations with numbers. 3 00:00:04,680 --> 00:00:10,200 So we're going to look at math operators. Let's go straight away and open a Python 5 00:00:10,200 --> 00:00:16,880 section and let me write a math expression there. 20 minus 10 divided by 7 00:00:16,880 --> 00:00:31,019 5 times 3 in the power of 2 and what we get is 2.0. So why did I write this a 9 00:00:31,019 --> 00:00:36,239 long expression? Well because I want to explain to you the order of operators so 11 00:00:36,239 --> 00:00:41,760 when you have multiple operators in an expression the one to be executed 13 00:00:41,760 --> 00:00:50,910 first is the exponent, so we have 3 in power of 2 here that will give us 9. 15 00:00:50,910 --> 00:00:56,120 So power is the first to be executed and also that is division and multiplication. 17 00:00:56,120 --> 00:01:00,210 Actually division and multiplication are on the same level. 19 00:01:00,210 --> 00:01:06,330 We're talking about order but the one that is first will be executed first so in 21 00:01:06,330 --> 00:01:11,640 this case division is the first one so what will happen here is Python will 23 00:01:11,640 --> 00:01:16,500 ignore minus for now, so it will divide 10 by 5 and it will 25 00:01:16,500 --> 00:01:30,180 give 2 then it will do 2 times 9. So again 10 divided by 5, 2 times 9, 19. 27 00:01:30,180 --> 00:01:35,220 And then we have the rest of the operators which could be a plus or minus so in 29 00:01:35,220 --> 00:01:45,299 this case we have minus so 20 minus 18. We have 2.0. You'd ask why we have 2.0? 31 00:01:45,299 --> 00:01:54,509 Because 10 divided by 5 gives 2.0. So division outputs a float in Python 3. 33 00:01:54,509 --> 00:02:00,540 If you are on Python 2, it would output an integer. Now to make your expressions 35 00:02:00,540 --> 00:02:10,590 look better, you'd want to remove the spaces for the power operator and also 37 00:02:10,590 --> 00:02:15,569 you do like that somehow you can read it better, 39 00:02:15,569 --> 00:02:23,550 so 2 times 9 and then 20 minus 18 and so on. You get the idea. 41 00:02:23,550 --> 00:02:33,599 You get 2.0 again and now if you want to execute the minus operator first 43 00:02:33,599 --> 00:02:38,569 you'd want to put that inside brackets. So why did we get 18? Well because 20 45 00:02:43,890 --> 00:02:52,940 minus 10 gives 10 and then 10 divided by 5 gives 2 and then 2 times 9 gives 18. 47 00:02:52,940 --> 00:03:02,459 That's the idea. And then you could also do this, put these in brackets and what 49 00:03:02,459 --> 00:03:13,890 would happen here is you know 10 here, 15 here in the power of 2, so 15 in the 51 00:03:13,890 --> 00:03:20,459 power of 2, and then 10, so 10 divided by 15 in the power of 2. Let's see what we get. 53 00:03:20,459 --> 00:03:25,920 Yeah we got that, so let's see if I was 55 00:03:25,920 --> 00:03:31,260 Right. 15 in the power of 2 we get 225. 57 00:03:31,260 --> 00:03:42,510 And then we got 10 on the other side, so 10 divided by 225. We get that number. 59 00:03:42,510 --> 00:03:46,349 So whenever you want to change the order of operators, you should use 61 00:03:46,349 --> 00:03:53,549 brackets and so I hope you get the idea and please try this out, so try to do a 63 00:03:53,549 --> 00:03:57,569 few operations with numbers to get used to it. And yeah, I'll talk to you later. 65 00:03:57,569 --> 00:04:00,379 Thanks. 3806