Dividing Decimals - By Anywhere Math
Transcript
| 00:0-1 | Welcome to anywhere , Math . I'm Jeff , Jacobson | |
| 00:02 | , and today we are dividing decimals . Here we | |
| 00:08 | go . All right , let's get right into it | |
| 00:27 | with our first example , 7.6 divided by four . | |
| 00:31 | Now , your first step is gonna rewrite it uh | |
| 00:34 | in like long division forms to help you to help | |
| 00:37 | you find the quotation . A lot of people have | |
| 00:40 | a hard time remembering which goes where , you know | |
| 00:44 | what I'm talking about is is we're going to rewrite | |
| 00:46 | it with that and people are wondering , well , | |
| 00:49 | I always forget what goes on the inside here and | |
| 00:51 | what goes on the outside . If that happens to | |
| 00:54 | you , just think of a problem that you know | |
| 00:56 | by heart , for example , I know six divided | |
| 01:00 | by three is too Okay , So then I'm thinking | |
| 01:04 | , well Is it gonna be the six here in | |
| 01:07 | the three here ? Or is it going to be | |
| 01:10 | the six here ? In the three here ? Right | |
| 01:14 | . You know , the answer has to be too | |
| 01:16 | . So whichever one gives you two , that's the | |
| 01:18 | way it needs to be . Well three goes into | |
| 01:20 | 62 times six because in the 30 and then you | |
| 01:24 | would have a 0.5 . So it's got to be | |
| 01:26 | that right . Which means the first number has to | |
| 01:32 | go on the inside . The next number has to | |
| 01:35 | go on the outside . That's what you're dividing by | |
| 01:38 | . Okay , so that's that can help you remember | |
| 01:40 | if you ever forget . So here 7.6 is going | |
| 01:43 | here just like the 61 there seven . So you're | |
| 01:47 | kind of basically crisscrossing right For is what you're dividing | |
| 01:50 | two x 7.6 , divided by four , divided by | |
| 01:55 | four . Uh Now when you're dividing with decimals , | |
| 02:00 | what the decimal point goes directly above ? Don't mind | |
| 02:07 | that The decimal point goes directly above where it is | |
| 02:10 | in your in your problem here , 7.6 . So | |
| 02:14 | it goes directly above . That's where it's going to | |
| 02:16 | be in a question so I like to put it | |
| 02:19 | right off the bat so I don't forget . Um | |
| 02:21 | So here we go now , we're just about four | |
| 02:23 | and the seven goes once that's four subtract , I | |
| 02:26 | got three . Bring down the six , Four into | |
| 02:30 | 36 is nine , that is 36 . So I | |
| 02:34 | am finished , there's nothing left here , so I'm | |
| 02:37 | done . So 7.6 divided by four is 1.9 . | |
| 02:44 | Okay , here's some to try on your own . | |
| 02:58 | All right , here's our second example 2.45 divided by | |
| 03:01 | 0.007 or 7000 . Um So again , first thing | |
| 03:08 | we're gonna do is rewrite it instead of like this | |
| 03:12 | we're gonna write it like with long division . So | |
| 03:14 | the 2.45 is being divided by 0.007 . Okay , | |
| 03:24 | so that's your first step . Alright . First step | |
| 03:28 | is to rewrite it now . In this example we | |
| 03:32 | are divided by a decimal . We do not like | |
| 03:35 | to do that . Okay we don't want to divide | |
| 03:38 | by a decimal . The first one the first example | |
| 03:41 | was much easier because this was a whole number . | |
| 03:44 | Now we can change this to a whole number simply | |
| 03:49 | by . Well if we move this once to three | |
| 03:53 | times The decimal .3 times to the right , that | |
| 03:56 | would make it seven which is a whole number , | |
| 03:59 | that's what we want to do but we can't just | |
| 04:02 | do that to this right ? If we only do | |
| 04:05 | it here and not here , our answer will not | |
| 04:09 | be the same . Not be equivalent to what it | |
| 04:11 | actually should be . So you have to do the | |
| 04:13 | same year I moved three times here , I'm going | |
| 04:15 | to move 123 here , there's nothing there . So | |
| 04:21 | I'm going to add a zero . This is basically | |
| 04:25 | just like equivalent fractions . You can think of it | |
| 04:27 | as Well . divided by 0.007 . If I want | |
| 04:35 | to make my denominator a whole number , I would | |
| 04:39 | just so I would just multiply That by 100 . | |
| 04:46 | Anything I do to the denominator , I need to | |
| 04:49 | do the numerator . So I multiply that by I'm | |
| 04:52 | sorry , 1000 . Right , Multiply that by 1000 | |
| 04:57 | . Which means I'm essentially just multiplying by 1,000 4000 | |
| 05:01 | . Just one . So nothing is actually changing . | |
| 05:04 | And then that would become seven over 2045 . Okay | |
| 05:13 | , So that's essentially what we're doing . We're not | |
| 05:15 | changing the problem . The quotation will still be the | |
| 05:18 | same as if I did this , or 2450 divided | |
| 05:23 | by seven . Okay . Uh It just makes it | |
| 05:26 | much easier for us , so that's what we're doing | |
| 05:28 | . Yeah , So that's step two is make sure | |
| 05:33 | you're dividing by whole number . Okay . Really really | |
| 05:37 | important . Do whatever you need to do , move | |
| 05:39 | it as many times as you need to divide by | |
| 05:41 | a whole number and then do the same thing here | |
| 05:44 | . Okay uh also what you're starting with your dividend | |
| 05:51 | does not have to be a whole number if you | |
| 05:54 | have a decimal here , that's fine . We don't | |
| 05:56 | care about that . All we care about is the | |
| 05:58 | divisor right here . That has to be a whole | |
| 06:01 | number . So From here I like to rewrite the | |
| 06:04 | problem so now it's seven which looks much better divided | |
| 06:09 | by 2450 . Okay now I also like to make | |
| 06:16 | sure I put my decimal point here so I remember | |
| 06:19 | that , that's where it is . So in my | |
| 06:21 | answer I'm gonna put it directly above for my question | |
| 06:25 | is going to go right there and now it's just | |
| 06:28 | long division . So seven into two . No that | |
| 06:30 | doesn't work . So seven into 24 goes three times | |
| 06:34 | . That's 21 . Subtract I get three . Bring | |
| 06:38 | down the 57 into 35 is five , that is | |
| 06:42 | 35 . Subtract I get zero but I'm not done | |
| 06:46 | because I still have a zero to bring down right | |
| 06:49 | ? That's why it helps to having that decimal point | |
| 06:51 | there . Bring down the zero while 17 year zero | |
| 06:55 | is zero . So now I am finished . So | |
| 06:59 | 2.45 divided by 0.7 is 300 and 50 . Okay | |
| 07:11 | and you can think of this like you're wondering well | |
| 07:14 | how did it increase so much ? We're dividing right | |
| 07:18 | , it's very similar to divided by fractions . You're | |
| 07:20 | dividing by a fraction essentially . That's less than one | |
| 07:25 | . Like a proper fraction . And we know when | |
| 07:27 | we divide by a proper fraction we're actually increasing the | |
| 07:30 | value . Okay so that's what's happening here . This | |
| 07:33 | is the death toll . That's less than one . | |
| 07:35 | So it's actually going to increase the value and increase | |
| 07:37 | it by quite a bit . Okay so 350 . | |
| 07:41 | Here's some more to try and your here's some more | |
| 07:44 | to try on your own . Thank you for watching | |
| 07:53 | . And as always if you like this video please | |
| 07:55 | subscribe . Mhm . |
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