Adding and Subtracting Mixed Numbers - 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 how to add and subtract mixed numbers and | |
| 00:06 | he won't sit back and enjoy . Okay , in | |
| 00:08 | this example , we're going to get three and two | |
| 00:11 | thirds entered this , we're going to add three quarters | |
| 00:15 | . All right . We've got a mixed number . | |
| 00:17 | We've got different denominators . It's pretty messy right now | |
| 00:20 | . These are not too bad that we deal with | |
| 00:21 | just a couple of steps . You do , The | |
| 00:23 | first thing we're going to do here is for this | |
| 00:25 | mixed number . We're going to change this into an | |
| 00:27 | improper fraction . Okay , So how do we do | |
| 00:30 | that ? There was a video where he looked at | |
| 00:31 | this what we do device to draw this , You | |
| 00:35 | can see here that we have 1 , 23 and | |
| 00:38 | that's cut into thirds there and we have that . | |
| 00:41 | So it was to color this in . We have | |
| 00:43 | these guys and that's our three and two thirds . | |
| 00:47 | So the way that we change this into an improper | |
| 00:49 | fraction is once again we're gonna go three times three | |
| 00:53 | here , that's these three groups of three . And | |
| 00:55 | we're gonna add the two , so three times three | |
| 00:57 | plus two . This is equal to 11 over three | |
| 01:02 | . And to this we're going to add three quarters | |
| 01:05 | . Okay ? So what do we do now ? | |
| 01:06 | Well , all we have is different denominators . Now | |
| 01:08 | . We we've already dealt with this kind of idea | |
| 01:10 | . It's not too hard . We just have to | |
| 01:11 | look for a common number that both three and four | |
| 01:15 | going to , and that number Is 12 . Okay | |
| 01:18 | , so three times one equals 12 . It's three | |
| 01:22 | times four . So we're going to multiply the top | |
| 01:24 | and the bottom by four . Uh the bottom here | |
| 01:28 | is a four which we multiply by four to get | |
| 01:30 | 12 and it's a three . So we're gonna multiply | |
| 01:32 | the bottom by three and it's topped by three . | |
| 01:34 | So what do we get when we do all that | |
| 01:36 | ? 11 times four , he's 44 . Uh Three | |
| 01:41 | times four is equal to 12 . And to this | |
| 01:44 | we're going to be adding three times three is equal | |
| 01:47 | to nine , and four times three is equal to | |
| 01:50 | 12 . Okay , what do we get ? We | |
| 01:52 | get this 40 for fast , nine is equal to | |
| 01:56 | 53 And that goes over 12 . We can simplify | |
| 02:00 | this further because we can turn this back into a | |
| 02:03 | mixed number . How many times has 12 ? Going | |
| 02:05 | to 53 while it goes in four times ? Uh | |
| 02:09 | that's 4 , 12-48 and we have a five remainder | |
| 02:12 | , so that's 5/12 and we can't simplify that any | |
| 02:17 | further . So that is our answer anyway , what | |
| 02:20 | about I'll give you a couple of examples to now | |
| 02:23 | do yourself . So let's give you three examples . | |
| 02:26 | Okay , so the first one . Nice easy one | |
| 02:28 | . Same denominators let's go 2/5 plus 1/5 . I | |
| 02:34 | don't think you'll have a much trouble doing that . | |
| 02:36 | The second one , let's use different denominators . Let's | |
| 02:39 | go one third plus three quarters and see what that | |
| 02:44 | equals for the third one . Let's use mixed numbers | |
| 02:48 | . Let's go two and 3/5 and we're going to | |
| 02:53 | take away one and one quarter and see what equals | |
| 02:58 | . All right , give these ago so to fits | |
| 03:00 | plus 1/5 . Well , we're going to keep the | |
| 03:02 | bottom number the same here . They're going to stay | |
| 03:04 | in fits and two plus one is equal to three | |
| 03:07 | . They're really simple . So that's right . Have | |
| 03:09 | you got that answer ? That's correct for this . | |
| 03:12 | Second question . One third plus three quarters . You're | |
| 03:16 | going to see that we have different denominators . We're | |
| 03:18 | going to look for a common number that both three | |
| 03:20 | and four go into which is 12 . Okay , | |
| 03:24 | common number they both go into is 12 . So | |
| 03:27 | we're going to multiply what by three to get 12 | |
| 03:31 | , it's going to be four . So we're going | |
| 03:32 | to do that to the top of the bottom . | |
| 03:34 | And what do we multiply before to get 12 ? | |
| 03:36 | That's three . So we do that to the top | |
| 03:39 | and the bottom . So what do we end up | |
| 03:41 | when we do this ? One times four is four | |
| 03:44 | , three times 4 is 12 to this . We're | |
| 03:47 | going to add three times three is nine and four | |
| 03:51 | times three is 12 . Okay , what do we | |
| 03:55 | get now ? Okay , four plus nine is equal | |
| 03:58 | to 13 And this also goes over 12 . We | |
| 04:03 | can simplify this further because this is a Improper fraction | |
| 04:08 | at the moment . 12 goes into 13 once and | |
| 04:11 | with one remainder , so this is one and 1/12 | |
| 04:16 | . Okay for the final question here , two and | |
| 04:18 | 3/5 take away one and one quarter . Well , | |
| 04:22 | we're going to first off change these mixed numbers into | |
| 04:25 | improper fractions and then we're going to have to play | |
| 04:27 | around the denominators . So let's first changes into improper | |
| 04:31 | fractions to and 3/5 . Okay , two times five | |
| 04:35 | is equal to 10 plus three is equal to 13 | |
| 04:39 | . That becomes 13/5 . One and one quarter one | |
| 04:44 | times four is four plus one is five And that | |
| 04:47 | becomes 5/4 . Okay , so now let's get this | |
| 04:51 | common denominator here . So a common number that both | |
| 04:55 | five and four go into An easy way doing this | |
| 04:58 | . Sometimes if you get really stuck , just go | |
| 05:00 | five times for it will tell you a common number | |
| 05:02 | . They go into that . If you can't think | |
| 05:04 | of one really easy . So five and four , | |
| 05:07 | both going to 20 , what would you multiply boy | |
| 05:12 | Five to get 20 here , and that would be | |
| 05:15 | four times four times for what would you multiply by | |
| 05:18 | four here to get 20 ? That would be times | |
| 05:21 | five times five . So what does that leave us | |
| 05:24 | with ? Okay , 13 times four . This is | |
| 05:27 | equal to 52 . five times 4 is equal to | |
| 05:31 | 20 . We're going to be subtracting here , five | |
| 05:35 | times 5 is 25 and four times 5 is 20 | |
| 05:41 | . What have we got now ? All right . | |
| 05:43 | 50 to take away , 25 is 27 . The | |
| 05:48 | denominator stays the same because the same denominator . Okay | |
| 05:52 | . And we can simplify this further . This becomes | |
| 05:54 | one and 7/20 anyway , hopefully that video was comprehensible | |
| 06:01 | for you . And in the next couple of videos | |
| 06:04 | we're gonna be looking at more playing around with fractions | |
| 06:06 | . I'm also gonna put another video up where it's | |
| 06:07 | going to be having a look at a shortcut . | |
| 06:09 | You can take to , uh , save yourself a | |
| 06:11 | bit of time when you do these , Okay ? | |
| 06:12 | Uh , so you can almost workout fractions instantly anyway | |
| 06:17 | . Hopefully that video was good for you . We'll | |
| 06:19 | see you next time . Bye . |
Summarizer
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OVERVIEW:
Adding and Subtracting Mixed Numbers is a free educational video by tecmath.
This page not only allows students and teachers view Adding and Subtracting Mixed Numbers videos but also find engaging Sample Questions, Apps, Pins, Worksheets, Books related to the following topics.
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