Multiplying Fractions Instantly - 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 in | |
| 00:03 | this video is how to multiply fractions and it's a | |
| 00:05 | pretty simple thing to do . So sit back , | |
| 00:08 | learn a couple of things and you'll pick this up | |
| 00:09 | really easy . So we got a couple of different | |
| 00:12 | types of fractions we're gonna be looking at to multiply | |
| 00:14 | here , but I'm gonna start with the one which | |
| 00:17 | I remember as a little kid made me really remember | |
| 00:19 | how to do this straight away , which was this | |
| 00:21 | one . Uh , I remember being told by my | |
| 00:24 | older brother at the time that a half times a | |
| 00:26 | half and he said , what do you think that | |
| 00:28 | is ? And I didn't get it right . I | |
| 00:29 | think I said one , but that's incorrect . Half | |
| 00:31 | 2.5 is a quarter . Yeah , literally what we've | |
| 00:35 | done here is the top times , top the numerator | |
| 00:37 | , times the numerator and the denominator times the denominator | |
| 00:41 | , two , times two equals four . But really | |
| 00:43 | , what's going on here ? If we could have | |
| 00:45 | a look at it , we can actually draw one | |
| 00:46 | half . And what we're actually really working out here | |
| 00:49 | , this is my half a year . But really | |
| 00:51 | what we're working out is we're working at a half | |
| 00:54 | of this . So what is a half of this | |
| 00:56 | , half ? And you can see here that a | |
| 00:58 | half of a half is a quarter . So it | |
| 01:00 | makes perfect sense . This is once again the top | |
| 01:04 | number of times the top number and the bottom number | |
| 01:07 | times the bottom numbers . That's really simple . Right | |
| 01:10 | ? So what about a harder example now , what | |
| 01:12 | about we do ? What is 2/5 multiplied by three | |
| 01:18 | quarters . And the idea is much the same . | |
| 01:21 | Top times the top the numerator times numerator and the | |
| 01:24 | denominator times the denominator . And you've got your answer | |
| 01:26 | there . Uh two times three is equal to six | |
| 01:30 | . five times 4 is equal to 20 one part | |
| 01:34 | that we have to do to this one though is | |
| 01:36 | this fraction here can be simplified . So two guys | |
| 01:39 | into both of these numerator and the denominator here , | |
| 01:42 | two guys in three times and Two goes into 2010 | |
| 01:47 | times . So our 6/20 can be simplified to 3/10 | |
| 01:51 | . There is a couple of variations you'll want to | |
| 01:53 | be aware of with this . So let me show | |
| 01:55 | you those first off , whatever you want to get | |
| 01:57 | something like this , whatever you want to get six | |
| 02:00 | times . Uh huh . Now like all multiplication , | |
| 02:04 | all multiplication really is is just repeated addition . So | |
| 02:07 | this is the equivalent of saying half plus a half | |
| 02:09 | plus a half plus a half plus a half plus | |
| 02:12 | a half , six times . How would you go | |
| 02:14 | about doing this , where you can go through an | |
| 02:15 | ad like that , but it's fairly inefficient . I | |
| 02:18 | think the easiest way to do this is to recognize | |
| 02:21 | that this six here can also be written as a | |
| 02:23 | fraction but over one . Okay , because six is | |
| 02:27 | also equal to 6/1 . 6 divided by one is | |
| 02:30 | equal to six And then we can multiply this by | |
| 02:34 | 1/2 . When we do this six times one is | |
| 02:37 | equal to 61 times two is equal to two . | |
| 02:42 | Okay , six divided by two . Our answer here | |
| 02:45 | is three . What about one more of those ? | |
| 02:48 | Okay , what about nine times 3/4 bit Nastier looking | |
| 02:53 | but they're not that bad . Okay , once again | |
| 02:55 | this nine here is going to become a fraction over | |
| 02:58 | one . So this becomes 9/1 . Multiplied by three | |
| 03:03 | over four . All right , top times Top bottom | |
| 03:06 | times bottom . Got your answer . Nine threes 27 | |
| 03:11 | One times four is equal to four . We can | |
| 03:14 | simplify this by turning it into a mixed number rather | |
| 03:18 | than improper fractions are 27 divided by four is equal | |
| 03:22 | to six . With three left over . We put | |
| 03:24 | this over four and that area to . Now the | |
| 03:27 | other type of variation you'll get is this one , | |
| 03:30 | for example , what is two and a quarter multiplied | |
| 03:35 | by three and one third . They're going to notice | |
| 03:39 | here we are dealing with mixed numbers , but that's | |
| 03:41 | no problem . We just have to turn these mixed | |
| 03:43 | numbers into improper fractions . Okay , So when we | |
| 03:47 | did this , remember two and one quarter we go | |
| 03:50 | two times four Plus 1 . 2 times four is | |
| 03:53 | equal to eight Plus one is equal to nine . | |
| 03:57 | And if you're not certain what I just did I | |
| 03:58 | have a video in the playlist attached to this in | |
| 04:01 | the description which looks at improper fractions and mixed numbers | |
| 04:05 | . Okay , This is going to be multiplied by | |
| 04:08 | Okay . 32 3rd becomes three times three Plus one | |
| 04:11 | is equal to 10 over three . What does this | |
| 04:15 | equal ? nine times 10 is equal to 90 four | |
| 04:19 | times 3 is equal to 12 . We can turn | |
| 04:23 | this now into a mixed number 90 , divided by | |
| 04:26 | 12 is equal to seven because 7 , 12 84 | |
| 04:32 | with sic over 12 . This can be simplified further | |
| 04:34 | because six goes into both the numerator and the denominator | |
| 04:38 | here , So we can end up with our answer | |
| 04:40 | of seven and a half . Okay , how did | |
| 04:44 | you go with that ? What about I'll give you | |
| 04:45 | a few examples to do by yourself . What about | |
| 04:48 | nice and easy to start off with ? We're just | |
| 04:50 | going to go , what is 3/4 times What ? | |
| 04:55 | About three before three or four squared ? What ? | |
| 04:57 | About seven times one half Nice and easy . And | |
| 05:04 | what about three and a quarter times to over three | |
| 05:10 | and we'll see what that equals . Okay , give | |
| 05:13 | them a flyer . Okay , so 3/3 times 4/4 | |
| 05:17 | , that's three quarters squared . Three times three is | |
| 05:19 | 94 times four is 16 . This can't be simplified | |
| 05:23 | anymore . So my answer is 9/16 seven times one | |
| 05:28 | half . Well , we're going to have to turn | |
| 05:29 | the seven here into a fraction , so it becomes | |
| 05:31 | 7/1 times one half . This is equal to seven | |
| 05:37 | times one is 71 times two is two . Yes | |
| 05:41 | . Seven divided by two is equal to three with | |
| 05:44 | one left over that becomes 3.5 . Three and a | |
| 05:48 | quarter . We're going to have to change into an | |
| 05:50 | improper fraction . Three times four is 12 plus one | |
| 05:54 | is 13 13/4 , multiplied by 2/3 . We don't | |
| 05:59 | have to change that to over three . This is | |
| 06:01 | equal to 13 times two is 26 . Four times | |
| 06:06 | three is 12 . So we can simplify this right | |
| 06:08 | now . As you can see the number two goes | |
| 06:10 | into both of these and then we'll take it into | |
| 06:12 | a mixed number 26 , divided by two is equal | |
| 06:15 | to 13 . 12 , divided by two is equal | |
| 06:18 | to six . This can be turned into a mixed | |
| 06:22 | number 13 , divided by six is equal to two | |
| 06:24 | with one left over . That one is going to | |
| 06:27 | go over This denominator here , 1/6 . Anyway , | |
| 06:31 | hopefully you found that video informative multiplying fractions . It's | |
| 06:35 | pretty easy . Right ? The next video we're going | |
| 06:37 | to have a look at dividing fractions and this is | |
| 06:39 | pretty simple as well . Anyway , thank you for | |
| 06:41 | watching . We'll see you next time . Bye . |
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Multiplying Fractions Instantly is a free educational video by tecmath.
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