Maths trick for fast addition - add faster than a calculator! - By tecmath
Transcript
| 00:00 | Welcome to Tech Math channel with videos . Can be | |
| 00:02 | looking at this how to add numbers together really , | |
| 00:06 | really quickly . Okay , so without much further ado | |
| 00:09 | , let's go . So how fast can you add | |
| 00:11 | these two numbers together ? Will give you a couple | |
| 00:13 | of seconds . We'll give you the question of 624 | |
| 00:20 | plus . 107 ready set go . Okay . So | |
| 00:28 | the answer issued have got should have been 731 . | |
| 00:31 | Now , if you've got that is the answer really | |
| 00:33 | , really good . If not , okay , we're | |
| 00:36 | going to be looking about how to do this today | |
| 00:37 | . So what this is going to be looking at | |
| 00:40 | is sort of going against what you've probably been taught | |
| 00:42 | in school were usually what you do is you add | |
| 00:45 | numbers from right here and you add them this way | |
| 00:50 | . Okay , So I'll give you an example here | |
| 00:53 | . If I was to rub this out , what | |
| 00:55 | you'd probably get used to it school is you got | |
| 00:56 | taught , we would write their numbers 624 down well | |
| 01:01 | , right , number 107 down . Put a little | |
| 01:04 | plus there to make it nice and neat and four | |
| 01:07 | plus seven there's 11 . So we put the one | |
| 01:10 | there , we carry the one and then one plus | |
| 01:13 | two is three plus nothing these three and then six | |
| 01:18 | plus one is seven . But it seems always a | |
| 01:22 | bit funny because often you don't really really want to | |
| 01:24 | write the numbers down all the time . So there's | |
| 01:25 | a bit of an easier way in my mind of | |
| 01:27 | doing these . And I'll show you how so I'll | |
| 01:30 | get rid of that there and I'll go through how | |
| 01:33 | I do it a different way , how I do | |
| 01:35 | it going from right to left now you need to | |
| 01:38 | practice is just a tiny bit , but it's not | |
| 01:40 | actually too hard to get . So first off I'd | |
| 01:42 | go six plus one is seven . Now before I | |
| 01:45 | got the seven down quickly look at this column here | |
| 01:47 | . Now if That would quickly make sure that doesn't | |
| 01:51 | add to anything more than 10 and it doesn't . | |
| 01:53 | So if it doesn't , I'll just put the seven | |
| 01:56 | down . Okay , I'll go into this one , | |
| 01:58 | two plus nothing . Well that's true . And so | |
| 02:02 | quickly before the two down , I look over this | |
| 02:04 | column and I see these two numbers add to more | |
| 02:06 | than 10 and they do they had to 11 . | |
| 02:08 | So instead of actually putting down to here , I | |
| 02:12 | put one more than two , Which is a three | |
| 02:16 | and then here four plus seven is 11 . And | |
| 02:19 | I just put the one here because I've already actually | |
| 02:21 | added that one there , I've already carried the one | |
| 02:23 | before I've actually done it . So hopefully you get | |
| 02:25 | what I mean there . I'll give you another example | |
| 02:28 | of this so we'll rub this out and I'll write | |
| 02:32 | something new on . Okay . What about some random | |
| 02:36 | 782 plus 125 . What does that equal ? Okay | |
| 02:45 | so doing it the same way as I was just | |
| 02:47 | doing it . First off we're going to add these | |
| 02:50 | two numbers together . So seven plus one is eight | |
| 02:53 | . And we look at this number , is it | |
| 02:55 | above 10 ? Well it is 10 so it's 10 | |
| 02:58 | or above . So I'm not only going to add | |
| 03:00 | seven plus one but I'm going to add another one | |
| 03:01 | to it as well . So first number is going | |
| 03:03 | to be a nine . Okay then I was left | |
| 03:07 | with zero before when the eight plus 20 it was | |
| 03:09 | 10 . So before I write the zero down I | |
| 03:12 | look at this number . Is it above 10 ? | |
| 03:14 | Two plus five ? No it's not at seven . | |
| 03:16 | So I can put my zero down and I can | |
| 03:18 | also put this seven down the answer . 907 a | |
| 03:23 | pretty good . Right , okay . Let's give you | |
| 03:28 | something a little bit a little bit further from this | |
| 03:33 | . What about say something like 586 plus 790 . | |
| 03:42 | To make the numbers a bit a bit bigger . | |
| 03:45 | Okay , so the answer to this would be five | |
| 03:48 | plus seven is 12 . So I go to write | |
| 03:50 | the 12 down but before I right there to there | |
| 03:53 | I look at these are above 10 . Yes , | |
| 03:55 | I write 13 down . Okay . What ? That's | |
| 03:57 | up to 17 . So Before I write the seven | |
| 04:00 | down here from the 17 , I look at this | |
| 04:03 | next numbers , Do they go to above 10 ? | |
| 04:05 | No , they don't . The six plus two is | |
| 04:07 | eight . So I put the 7 to 7 down | |
| 04:09 | and I put the down pretty good . Right ? | |
| 04:13 | All right . So if you follow this method and | |
| 04:15 | you should you actually hit this stage where you probably | |
| 04:20 | you won't even want to start even adding them on | |
| 04:23 | a bit of paper . You can start adding them | |
| 04:25 | off the top of your head . Okay ? I | |
| 04:27 | hope that works for you . See you next time | |
| 00:0-1 | . |
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