Double Numbers - How to double any number instantly. - By tecmath
Transcript
| 00:00 | Good day and welcome to the Tech Math Channel . | |
| 00:02 | What would they be having a look at is in | |
| 00:04 | this video is an easy way of doubling numbers . | |
| 00:07 | Okay , so how to instantly double numbers . Let's | |
| 00:11 | go . So what is the double of uh , | |
| 00:14 | 328 ? Give you two seconds to answer that 1 | |
| 00:18 | , 2 . Did you get the answer of 656 | |
| 00:24 | if so ? Very good . Congratulate yourself . You | |
| 00:27 | did really well . Okay . What about the double | |
| 00:30 | of 184 Did you get the answer of 368 . | |
| 00:38 | Okay . What about the double Over 289 . Did | |
| 00:44 | you get the answer of 578 . Now , if | |
| 00:48 | you've got all those and you got them before I | |
| 00:51 | could write them down or at the same time I | |
| 00:52 | was writing them down , congratulations . You know what | |
| 00:56 | ? You probably don't need to watch this video anymore | |
| 00:58 | . But if you tend to still be trying to | |
| 01:01 | work them out , then this video is aimed at | |
| 01:03 | trying to increase your ability to be able to double | |
| 01:06 | numbers and there's a couple of little tricks with this | |
| 01:08 | . How do we do it instantly ? The trick | |
| 01:10 | is really simple . And the way I'll show you | |
| 01:13 | is by giving you an example . Okay , it's | |
| 01:15 | just a couple little things to remember when doubling numbers | |
| 01:18 | and the tricks all of a sudden you'll you'll be | |
| 01:21 | getting ah instant answers . So what's the double of | |
| 01:26 | 359 now ? I'm going to work through this example | |
| 01:31 | , so I'll show you how I worked this out | |
| 01:34 | . First off , what I do is I look | |
| 01:36 | at The 1st 2 Digits here . Okay , Double | |
| 01:41 | of 35 . You probably realize It's 70 . I'm | |
| 01:45 | going to write it down there , but generally I | |
| 01:46 | wouldn't write this down yet . Okay . Usually what | |
| 01:49 | I do now is I look at the next part | |
| 01:51 | of this answer . Okay . The next question you | |
| 01:55 | have to ask yourself about this part . This part | |
| 01:57 | here is to say is this number above 4 ? | |
| 02:00 | In this case ? It is If the numbers above | |
| 02:03 | four we add one to this number here . Okay | |
| 02:07 | so We double 35 we get 70 , this is | |
| 02:12 | above four . So we add one and we get | |
| 02:14 | 71 . Now if we had a double this number | |
| 02:18 | we would have got 18 . So we've already added | |
| 02:21 | the one that was one we added over here . | |
| 02:23 | We just put what the units part Of our answer | |
| 02:25 | would have been will be doubled nine . So he | |
| 02:27 | gets 718 . Did you get that ? If not | |
| 02:32 | ? Don't despair . I'll go through a few more | |
| 02:34 | answers are a few more examples . Okay . And | |
| 02:38 | we'll see how you go . What about if we | |
| 02:40 | are do say something like I'll do a different one | |
| 02:48 | . So We look at this 43 here , the | |
| 02:52 | double of that . So even before that you could | |
| 02:54 | look at this and think well I have to add | |
| 02:56 | one to my answer . Okay . So double of | |
| 02:59 | 43 is it seeks do that in a different color | |
| 03:04 | plus I'm gonna add my one . So it's going | |
| 03:07 | to be 87 And this the units part of our | |
| 03:12 | answer . Six doubled his 12 would have been a | |
| 03:14 | two . So that's how you instantly double that number | |
| 03:18 | . The answers . 872 . Okay . Let's have | |
| 03:24 | a look at another one . What about the number | |
| 03:28 | ? 360 four . Okay , so we double before | |
| 03:37 | that . We can look at this number here and | |
| 03:38 | we can say its Below . That's four or below | |
| 03:41 | . So it's not going to we're not going to | |
| 03:43 | have to add one . So this number here we | |
| 03:44 | go 36 . We double it and we get 72 | |
| 03:48 | . Mhm . Okay . And this number now we | |
| 03:52 | just double and get eight . Okay . All right | |
| 04:00 | . What about I give you a couple of examples | |
| 04:03 | here , so I'll give you a few examples here | |
| 04:07 | . What about the number ? 283 ? We'll give | |
| 04:13 | you another one . This is doubles , doubles . | |
| 04:20 | We'll give you another one of 300 and seven And | |
| 04:27 | another one of 5 one . Uh No . Ok | |
| 04:35 | . That'll do So I see here you go with | |
| 04:37 | those . You should be able to actually start rolling | |
| 04:39 | down the answers automatically . Okay , So This is | |
| 04:43 | not above force we're not going to have to have | |
| 04:45 | 128 doubled 56 . Three doubled is six . This | |
| 04:52 | one is above four . So we are going to | |
| 04:53 | have to add one 30 doubled its 60 61 . | |
| 04:58 | This doubled would have had a units answer of four | |
| 05:01 | because it was 14 . This one here is above | |
| 05:04 | four . So we're going to add a 151 doubled | |
| 05:08 | Is 102 . Annoyed . Well , that would have | |
| 05:13 | doubled to give 18 . So we're gonna put the | |
| 05:16 | eight down there . Okay . Hopefully it did really | |
| 05:19 | good on those . If not keep practicing at them | |
| 05:22 | , you will get better at them anyway . We'll | |
| 05:25 | see you next time . Bye . |
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