How to easily multiply any number by twelve - By tecmath
Transcript
| 00:0-1 | Good day . Welcome to the Tech Math channel . | |
| 00:01 | What we're going to be having a look at this | |
| 00:03 | video is a way of multiplying by the number 12 | |
| 00:06 | fairly quickly . So let's get straight into it . | |
| 00:08 | Okay ? So say you are asked to multiply the | |
| 00:11 | following number by 12 , 314 times 12 . Now | |
| 00:17 | , The way that we do this is we're going | |
| 00:18 | to follow two simple rules and these are as follows | |
| 00:22 | as we go along . We're going to be looking | |
| 00:23 | at each number in the number when multiplied by 12 | |
| 00:26 | . We're going to double it . That's the first | |
| 00:28 | part . And then we're going to add the neighbor | |
| 00:30 | to the right . And that's all we're going to | |
| 00:32 | do . We're going to get our answer by doing | |
| 00:34 | this . Okay . So let's start out straight away | |
| 00:37 | . So first off , four , we double it | |
| 00:40 | . That's the first part of our thing . Then | |
| 00:41 | we add the number to the right . There's no | |
| 00:43 | no for the right . So four doubled is eight | |
| 00:46 | . That's the first part of our answer . The | |
| 00:48 | next thing we do is we go to the next | |
| 00:50 | part . Okay . one doubled is too Okay so | |
| 00:54 | we double that we get to plus four is 6 | |
| 00:58 | . Alright , next part of our answer . What | |
| 01:00 | we do is we double three , we get six | |
| 01:02 | plus one is seven . Okay ? Absolutely zooming through | |
| 01:05 | this year . Almost finished . I'm just gonna put | |
| 01:09 | a zero here and you're gonna see why I put | |
| 01:11 | this here because we're not quite finished yet because we | |
| 01:14 | can still uh what we can do is we double | |
| 01:16 | zero , we get zero plus three is three . | |
| 01:21 | So what you're going to notice with this is this | |
| 01:24 | is now an answer but just make sure you get | |
| 01:27 | the zero here . Okay . So it's a really | |
| 01:29 | really important thing to do but that is our answer | |
| 01:31 | . That's the entire thing . Pretty cool method . | |
| 01:33 | Yeah , I can't tell you what , let's go | |
| 01:36 | through one more example , this again , just double | |
| 01:39 | the answer and add the name to the right , | |
| 01:42 | okay , you're going to see this in a lot | |
| 01:43 | of videos coming up to that . We're making um | |
| 01:46 | , this method works . A similar method , works | |
| 01:49 | for a whole lot of numbers . Okay , so | |
| 01:51 | what about we do a much bigger number this time | |
| 01:53 | ? What about we do say ? Oh , just | |
| 01:56 | write this number down 443 oh five to And we're | |
| 02:03 | going to multiply this by 12 . So 440 , | |
| 02:08 | times 12 . Same method , Because we're multiplying by | |
| 02:11 | 12 , we're going to double the number and add | |
| 02:14 | the number . Next one that had the neighbor . | |
| 02:16 | Okay , so double of two years , four Double | |
| 02:21 | of five is 10 plus two Is 12 . So | |
| 02:25 | I'm gonna put the two down here . I'm not | |
| 02:27 | gonna write the entire 12 and I'm going to carry | |
| 02:29 | that one across . Okay , so with this you | |
| 02:31 | do have to carry numbers across . Let's go the | |
| 02:33 | next part of our answer . Double of zero is | |
| 02:36 | zero plus five is five plus one is six . | |
| 02:39 | Okay , Double of three is six plus zero is | |
| 02:42 | six . Double of four is eight plus three is | |
| 02:46 | 11 carry that one across . Double of four is | |
| 02:50 | eight plus four is 12 plus one is 13 carry | |
| 02:54 | that little one across . And you might not forget | |
| 02:58 | this one with that little zero just here . Okay | |
| 03:00 | , don't forget about him . All right , so | |
| 03:02 | double zero is zero plus four is four plus one | |
| 03:08 | is five . Our answer is a really , really | |
| 03:11 | big telephone number of an answer . 5,316,624 . So | |
| 03:17 | how did you go with that ? Hopefully you find | |
| 03:19 | that a really , really cool method , I must | |
| 03:21 | say . I'm always gets a bit excited so I'm | |
| 03:23 | a bit biased with this . I I love it | |
| 03:25 | , but I'm crazy with all this sort of stuff | |
| 03:28 | . So , you know . All right . Um | |
| 03:31 | Yeah , This is fairly similar . You might have | |
| 03:33 | noticed actually to an 11 times table trick by the | |
| 03:35 | way . So if you haven't seen this , I | |
| 03:36 | recommend you have a look at this 11 times table | |
| 03:39 | trick . I'll put a link up for that . | |
| 03:41 | If I remember sometimes I forget to do this . | |
| 03:43 | I say here's a link and it doesn't come up | |
| 03:45 | . So if I haven't . Um hey , sorry | |
| 03:47 | . All right . Anyway , thanks for watching see | |
| 03:49 | you next time . Bye . |
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