01 - Learn Order Of Operations (5th Grade Math) - Free Educational videos for Students in K-12

01 - Learn Order Of Operations (5th Grade Math) - By Lumos Learning

Transcript


00:00	Hello . Welcome to this lesson in mastering fifth grade
00:03	math here . In this lesson , we're going to
00:05	talk about the topic of order of operations . So
00:09	as we go through this lesson will be working examples
00:12	step by step to teach you the concepts of what
00:13	we call order of operations in math . And then
00:16	we'll also be going on through all of the other
00:18	lessons in this batch in the series here , taking
00:21	every single concept , step by step . So let's
00:24	follow on through here . The one thing I want
00:26	to make sure and let you know is that after
00:28	you finish watching this lesson and you'll understand everything ,
00:31	I want you to work all of these problems on
00:33	a separate sheet of paper yourself . And then I
00:35	would like you to get the workbook the worksheets out
00:38	and walk all of those problems . When you're confident
00:41	that you understand everything you're doing well , then you
00:43	can move on to the next topic . That's the
00:45	way to succeed in math , so we have this
00:47	concept called the Order of Operations . What it basically
00:50	means is , up till now , you really have
00:52	gotten good at adding and subtracting numbers and multiplying and
00:56	dividing numbers . We've also done quite a bit of
00:58	work with fractions , but it turns out that there
01:01	is a specific order that we are supposed to do
01:04	, adding and subtracting and multiplying and dividing when we
01:07	have a bigger problem . So let me tell you
01:09	what that order is . I'll just write it on
01:11	the board and then you'll have it here . And
01:13	then as we work a lot of problems , you'll
01:15	see very quickly this very , very simple . So
01:18	this whole concept concept is called the Order of Operations
01:25	. And basically , as I said before , it
01:27	just tells you how you should solve your problems .
01:30	What order ? You should solve your problems . So
01:32	, um , number one the number one thing you
01:35	do when you're solving a problem that involves adding ,
01:38	subtracting , multiplying , dividing , uh , is we
01:41	have the concept of parentheses in math , so I'll
01:44	get to that a little bit later . We'll talk
01:46	about it when we do our problems , but number
01:47	one you want to always do inside whatever is inside
01:53	the parentheses first , doesn't matter what else is happening
02:02	in your problem . If you see any parentheses in
02:04	your problem , you have to do what's inside of
02:05	those guys ? First number two . The next thing
02:08	and the order is you want to do multiplication and
02:17	division . Yeah . Mhm . And what I when
02:23	I say do multiplication and division ? I'm talking about
02:25	doing it left too , right ? What this means
02:31	is , if you have two times two divided by
02:33	six times five , then you're doing multiplication and division
02:37	as you read , left to right across the page
02:40	. All right ? And then the last thing is
02:42	, and there's only three rules , So this is
02:43	the third one . The final thing you want to
02:45	do is you want to do adding and subtract .
02:53	You want to add some tracked left to , right
02:55	? Mm . Okay . Yeah . All right .
03:01	So that's the basic idea . Um , as you
03:03	get higher and higher into math , there are a
03:05	few additional rules in order of operations . We'll get
03:07	to those as you get higher in math . But
03:09	right now , at this level , what we're trying
03:10	to do is we're trying to show you that sometimes
03:13	you run into these things called parentheses . When you're
03:15	solving problems , I'm gonna show exactly what that is
03:17	in Just a minute . Don't worry about it's very
03:19	simple . And also we're trying to show you the
03:21	rules that you follow when you're solving these problems .
03:24	When you're calculating the number One thing you do ,
03:27	very first thing you do is you always do whatever
03:29	is inside of the parentheses first , all right ,
03:33	After you've done that , then you do multiplication and
03:35	division next and you do it left to right just
03:38	like you read a book . And then after that
03:40	you do adding and subtracting left to right just like
03:43	you read a book . So these are the three
03:44	rules . We're going to use these over and over
03:46	and over again . So let's just get started by
03:48	solving a real problem . Because , you know ,
03:50	a lot of times you talk about these things ,
03:52	but until you see it , you don't really know
03:54	what I'm talking about . So let's say we have
03:56	the problem five times six minus four , and I
04:00	ask you , I want you to calculate what five
04:03	times six minus four is . So a lot of
04:05	students would take five times six and then we'll get
04:08	the answer of that . And then they would subtract
04:10	four , all right , but also some other students
04:13	might say , Well , let me take six minus
04:15	four and then multiply by five . What is going
04:18	to give me the correct answer ? Well , let's
04:20	follow the order of operations . You have to do
04:23	it in a specific order . Otherwise you get the
04:24	wrong answer . So let's show you what that is
04:27	. First it says , Do what's inside of the
04:29	parentheses first . There are no parentheses in this problem
04:32	. So you don't even worry about number one .
04:33	It doesn't apply . All right , number to do
04:36	multiplication and division left to right . So multiplication division
04:40	comes before adding and subtracting . That means that this
04:43	multiplication here has to be done before the subtraction because
04:46	we go down the order here . This is the
04:48	most important . This is the next thing we do
04:50	, and this is the last thing we do .
04:52	So adding and subtracting basically is always going to be
04:55	last in every problem you do . So since we
04:58	have multiplication here , that step Uh , order number
05:02	two or step number 25 times six . The way
05:06	we write this down , as we say , this
05:07	is 30 . Now we still have the minus four
05:10	, so we just carry it along for the ride
05:11	so we see exactly what we did , and your
05:13	teacher will see exactly what you did . Five times
05:16	six gives you 30 . The minus four has not
05:18	been done yet because multiplication came first . All right
05:22	. And then now we look at this line and
05:25	we see What do we have left to do ?
05:26	The only thing left is a subtraction . We've done
05:29	everything else , adding and subtracting comes last . So
05:32	we go ahead and do this . So the answer
05:34	here 30 minus four is 26 this is what you
05:38	would circle on your test . This guy is the
05:40	correct answer . If you put this in the calculator
05:42	or a computer or doing it by hand is we've
05:45	done here 26 is the correct answer . Now I
05:48	want to show you how a lot of students get
05:51	into trouble if you don't follow order of operations .
05:53	So I'm gonna change colors and I'm going to change
05:56	colors to kind of this pink color here . So
06:00	let's say we have five times six minus four .
06:04	The way we were supposed to do is we multiplied
06:06	first . Then we did the subtraction . But let's
06:08	say somebody doesn't know this very well and they decide
06:11	to do the subtraction first . Now this is clearly
06:14	wrong because the subtraction is the very last thing we
06:17	do . But let's say somebody does it . So
06:19	six minus four gives you two that comes from this
06:23	. And then let's say you still chose . You
06:25	used to put the five out to be multiplied as
06:28	the last step . So let's go ahead and see
06:29	what happens here five times to the only thing left
06:32	to do in the problem would be 10 . So
06:34	one student who did it correctly gets the answer of
06:36	26 . Another student who does the answer incorrectly gets
06:41	10 . So who's going to get the right answer
06:43	? Well , not the guy who did this because
06:45	he did it wrong or she did it wrong .
06:47	Six minus four is two and five times two is
06:50	10 . But the way that you do it here
06:52	is backwards of how you're supposed to do it .
06:54	You always do parentheses first . Then you do multiplication
06:57	and division . And then you do adding and subtracting
07:00	. Here we did everything out of order . So
07:02	just to make sure you know this is wrong ,
07:03	I'm gonna put a big X through this . That
07:05	is wrong . I'm not going to show you in
07:07	every problem the wrong way to do it . But
07:09	I want to show you that the order matters .
07:12	If you don't do the order correctly , you're gonna
07:13	get the total wrong answer and and just not do
07:16	it right . So let's go ahead and continue on
07:20	here and get some more practice . We're just gonna
07:22	do a lot of these things . What if I
07:23	have 36 divided by six minus four Again ? Some
07:30	students might look here and say , Well , I've
07:32	got subtraction . I've got division . What do I
07:34	do first ? Well , you go to your order
07:36	of operations . We check for parentheses first . There
07:39	are no parentheses here . Then we do multiplication and
07:42	division . Well , here's some division . So 36
07:45	minus six . I'll switch colors . 36 . I
07:48	should say divided by six is going to be six
07:51	, and then we still have the minus four .
07:54	So this is equal to six minus four . Now
07:56	, The only thing remaining to do and the problem
07:57	is subtraction that comes dead last six minus four is
08:00	two . So the answer is to all right .
08:03	So as we work these problems , I just want
08:06	you to remember three things are very easy . Do
08:08	parentheses first , then do multiplying and dividing . Then
08:12	do adding and subtracting . You're adding , subtracting should
08:14	always come last . So as we continue to work
08:18	these problems , I want you to kind of keep
08:19	that in mind because those rules are never going to
08:21	change in math . You're always going to be using
08:24	these rules . Now . What if you have the
08:25	problem ? 10 plus seven times four . Right now
08:29	, here's the correct way to do it . The
08:31	first thing you look and see is Do I have
08:33	any parentheses in this problem ? And I don't ,
08:36	so I don't even worry about parentheses . The next
08:38	thing I do is I Look , do I have
08:40	any multiplication or division ? Because that is the next
08:43	thing on the list , and I see that I
08:44	have seven times for now . I also have an
08:47	addition here , but we know that we always do
08:49	addition and subtraction last so we don't do that .
08:52	First , we always do the multiplication or division first
08:55	, so I know it seems a little weird ,
08:57	but what you're gonna do is skip over here and
08:59	say seven times four , um , is 28 now
09:03	? Don't forget , you still have to add the
09:05	10 to it . So you write it just like
09:06	this for your next steps . 10 plus 28 and
09:10	now to do the final part of the problem .
09:12	You know that 10 plus 28 is 38 there's nothing
09:16	else left to do because that edition was the last
09:18	thing in the problem . So notice we followed our
09:21	order of operations . First . We did multiplication .
09:23	We did it right here . And then we did
09:26	the addition . We get an answer of 38 .
09:27	A lot of students will get the wrong answer because
09:31	they'll do this edition . 1st 10 plus seven is
09:34	17 , right ? And then they'll multiply the 17
09:37	that they got . Times four . That's going to
09:39	give you the wrong answer . 17 times four is
09:43	not 38 . All right , so you have to
09:46	do it right . You do princes first , then
09:48	multiply . Divide , then addition and subtraction . And
09:51	I keep saying it over and over again because it's
09:53	honestly one of the most important things you can learn
09:55	in math is order of operations now for this problem
09:59	, we're gonna introduce this idea of a parentheses .
10:01	18 divided by two times six , divided by three
10:09	. Now here , if you've never seen parentheses in
10:11	math before , it looks a little bit weird .
10:13	Um , but the way you read parentheses in math
10:16	is just in terms of the order of operations .
10:19	All parentheses mean the only reason we have parentheses is
10:23	because we want to force what's inside of the parentheses
10:26	to happen first , because parentheses are always number one
10:29	on the list . All right , so we can't
10:32	do this multiplication that's in the middle first , because
10:35	we have to handle what's inside the parentheses first .
10:39	So the way you handle this , as you say
10:40	, Well , inside this parentheses is 18 divided by
10:44	two and 18 , divided by two is nine .
10:47	So we put in nine here , and you can
10:48	kind of keep the princes here For now . We'll
10:50	keep the multiplication for now . And inside this parentheses
10:53	, the six divided by three . And you know
10:55	that that is equal to two . So here we
10:57	have parentheses . Nine parentheses to Since there's only one
11:01	number inside of these parentheses in this step here ,
11:04	we can kind of remove the princes . We don't
11:06	really need them anymore . I'm gonna leave them here
11:07	for this problem . Parentheses only makes sense when you
11:10	have multiple things going on inside . If you do
11:13	everything and you just get one number , then you
11:14	can drop the parentheses . They don't even matter anymore
11:17	. Okay , so we've done everything inside the parentheses
11:20	, and now the only thing that we have left
11:22	to do is this operation the multiplication . Because we
11:26	go through the order of operations . We've done the
11:27	parentheses . Now we look for addition and subtraction .
11:30	We don't have any . Next . We look for
11:32	multiplying and division , and we do that like this
11:36	. So nine times two is 18 . 18 is
11:40	the final answer to that problem . All right ,
11:42	So you don't wanna accidentally be doing things like two
11:45	times six first , you know , or anything like
11:49	that , because you want to handle what's inside this
11:50	parentheses . What's inside this parentheses ? Once you have
11:53	those , then you handle the other operations , and
11:55	we always do adding subtracting before multiplying and dividing .
11:59	All right , let's go into the next problem .
12:01	Going to quite a few of these . What if
12:02	we have something like five times 20 minus three plus
12:09	eight . Okay , so now the problems are getting
12:12	a little bit bigger , and this looks a little
12:14	bit complicated at first . If you get confused at
12:16	what to do , just go back to your order
12:18	of operations . First thing , check for parentheses ,
12:21	then multiplying , dividing , then adding and subtracting .
12:25	But notice in this case that we have a parentheses
12:28	here , so we know we have to do what's
12:29	inside the parentheses . Now here's the catch . Whenever
12:32	I showed you the order of operations , I said
12:33	, Do the parentheses first , then new multiplication division
12:36	. Then do adding and subtracting . If you're working
12:39	inside of the parentheses , whatever is inside of there
12:42	, you still need to follow this order . So
12:44	we first look inside of the parentheses and we look
12:47	for any multiplying or dividing inside of the parentheses first
12:51	, and we don't see any . So in this
12:53	case we can do the subtraction first because it's inside
12:56	the parentheses and inside the princes , we always look
12:59	for adding a multiplication and division first and then adding
13:02	and subtracting so everything outside the princes that we're not
13:07	able to touch right now . But inside if you're
13:10	20 minus three is 17 . So we put a
13:14	17 here that comes from that . Now the times
13:17	five that's on the front end and the plus eight
13:20	that's on the back and that all stays the same
13:22	. Now , I could put parentheses around 17 because
13:25	you know , there was princess here . But once
13:27	I've solved everything inside of the parentheses , Um and
13:31	it's just one number left from that . I can
13:33	drop the princess . The princess is really only only
13:35	make any sense when there's multiple things happening because you're
13:38	trying to group operations . Once you've done it all
13:41	, then you can just drop it . So what
13:42	we have now is five times 17 plus eight ,
13:47	and I'm going to ask you How do we solve
13:48	that ? Well , we've already done parentheses . That's
13:51	done . So then we look for multiplying and dividing
13:53	, and we do that left to right . So
13:55	here we see five times 17 . We're gonna do
13:57	that . First , we're not gonna do any plus
13:59	eight because that comes last . So what we'll have
14:03	then five times 17 is going to give you 85
14:08	then we carry the plus eight down because we have
14:10	to do that in the very last step . The
14:12	only thing remaining is addition , and we know adding
14:15	, subtracting does come last . So 85 plus eight
14:17	is 93 that is the final answer . You need
14:21	to make sure you understand the concept of what we're
14:24	doing here because a lot of students will get confused
14:26	. If you don't know the order of operations ,
14:28	you might try to multiply five times 21st . Or
14:31	you might try to do this something with this three
14:34	plus an eight first , and you can't . There's
14:37	a specific way of doing it . You do inside
14:39	the princess . Once you're zoomed inside the princess ,
14:42	you always look for multiplication and division first , then
14:45	adding and subtracting inside the princess . Once we did
14:48	that , then you bounce out of it and you
14:51	go left to right , multiplying and dividing and then
14:53	left to right , adding and subtracting . So this
14:57	whole process becomes a whole lot more comfortable to you
15:01	the more and more of these things we do .
15:03	So let's say we have seven times seven minus three
15:07	inside of some parentheses . How do we handle this
15:09	one ? Okay , well , first we check for
15:12	Princess and we see we have parentheses Now inside of
15:15	here , we only have one thing to do .
15:16	Seven minus three . There's no multiplying or dividing in
15:19	here , so we don't worry about that . We
15:20	just go to the subtraction . Seven minus three is
15:22	four . We can drop the princes now because we've
15:25	tackled what's inside of there the time seven remains because
15:28	we haven't done that yet . And then the very
15:31	last thing that we do is seven times four is
15:33	28 that is the final answer . You know ,
15:37	if you want to keep parentheses around here , I
15:40	mean , you can just to remind yourself that this
15:42	four came from the princess . It's okay , but
15:45	still , you're just gonna multiply seven times for at
15:47	the end of the day because that is what's going
15:49	to give you the final answer there . There's nothing
15:51	else left to do after you've handled the princes in
15:53	this case . All right , let's do 10 plus
15:58	10 divided by two , divided by five . Alright
16:03	, so here's a problem . First thing we do
16:05	is we look for parentheses . We see that we
16:08	have princes , so we know we have to do
16:09	what's inside here first . But once we're inside of
16:12	their first , we look for multiplying and dividing .
16:14	We do those first , then we look for adding
16:16	and subtracting . So we see that we have a
16:18	division here . 10 divided by two is five .
16:21	And just to remind you all , keep the princes
16:23	around the five to show you that we've handled it
16:25	. The plus 10 remains in the divided by five
16:27	also remains . Okay , there's no adding or subtracting
16:31	in here . We've done everything that we need to
16:33	do . We've done the division first , so we
16:35	have a five here . Now we go to the
16:38	next step . We look at this , we've done
16:41	the parentheses . The next thing we do is we
16:42	look for multiplying and dividing the very next step after
16:46	parentheses . Well , we have addition here , but
16:49	we have division over here , so we need to
16:52	do this . First five divided by five is one
16:55	. We still have our plus 10 that we haven't
16:58	handled yet . Okay . And the very last thing
17:01	, there's nothing else to do . 10 plus one
17:03	is 11 . So addition and subtraction come last .
17:06	Another way to think about it is the only time
17:09	addition and subtraction don't come last is if they're inside
17:11	parentheses , because then you have to do them first
17:14	. So you just kind of have to keep an
17:15	eye on on the ordering . And there's only three
17:18	rules at this level that you need to know .
17:21	Okay , Now let's go and switch this over and
17:25	do a couple more additional problems just to give you
17:28	some extra practice . What if you have eight times
17:33	eight minus nine times to How do we handle something
17:37	like that ? First we look for parentheses and we
17:40	see that we don't have any princes , so we
17:42	forget about that . Then we look for multiplying and
17:44	dividing . Now we do multiplying and dividing left to
17:48	right . We do multiplying and dividing left to right
17:51	. This subtraction is not going to happen until the
17:54	very , very end . So just forget about trying
17:55	to subtract anything . But we see that we have
17:58	a multiplication here . We're gonna go left to right
18:00	. Eight times eight is 64 right ? Nine times
18:05	two is 18 . So we can do all this
18:08	at once . And they're linked by the subtraction .
18:10	It has to come later . You see what I
18:12	mean ? So we do this to make 64 .
18:15	We do this to make 18 because we're reading left
18:17	to right . And we're doing the multiplication or division
18:20	. But the any subtraction or anything like that that's
18:23	happening . We wait till later . And the final
18:24	answer 64 minus 18 . If you forget how to
18:28	do that 64 18 , you can just subtract to
18:31	the side we can borrow . Here , make this
18:33	a five . This 14 minus eight is gonna give
18:36	me 65 minus one is gonna give me four .
18:38	So the answer is 46 46 just like that .
18:43	So you need to do the multiplication and division first
18:47	left to right . That's what we mean by left
18:49	to right . We do it like this . And
18:51	then we do addition and subtraction for the very last
18:54	step . Now , what if we have 24 divided
19:01	by four , divided by two times three . Now
19:05	, here's where left to right is going to become
19:06	even more important . Okay , we first look for
19:09	parentheses . We don't see any princes . So the
19:12	next thing we do is look for multiplication and division
19:14	, and we do it left to right . Right
19:15	? Left to right . So we see we have
19:18	a bunch of stuff going on here . We have
19:20	a division here . We have a division here .
19:22	We have multiplication here , and these are all linked
19:24	together , so you can't really do them all at
19:27	once . So what you really should do is do
19:29	them left to right . Okay , So what we
19:31	have is in the first step and the first step
19:35	, we have 24 divided by four . What is
19:37	that ? Equal six . Now , let's just carry
19:40	the divide by two multiplied by three . From this
19:42	, let's just carry that to the next problem .
19:45	This became a six . Now we go left to
19:47	right . Multiplication and division six divided by two is
19:50	three . Now we have the times . Three will
19:52	just leave that along for the ride . And then
19:54	finally , three times three is nine . So the
19:57	answer to that problem is nine . This is what
20:00	we really mean when we say multiply and divide left
20:03	to right . Okay . When you look at that
20:06	, you you can do the first multiplication or division
20:09	. Then bring the problem down . Then do the
20:10	next multiplication or division . Bring the problem down and
20:12	do the final multiplication or division . Bring the problem
20:14	down . Since we didn't have any addition or subtraction
20:17	in that problem , then we didn't have to worry
20:19	about it . We just did the multiplying and dividing
20:20	left to right . If you start doing things out
20:23	of order , then you're not going to get the
20:24	right answer . Now , I want to contrast that
20:27	to what we have up here . We could have
20:28	done this also , uh , in more of a
20:31	left to right kind of way . In fact ,
20:32	I'll do this again for you just to show you
20:34	I showed you the first time that we kind of
20:35	do both of these separate and link them with the
20:37	subtraction . Let me just show you really quickly how
20:40	you would do that a little bit with a little
20:42	bit more steps to show . Since we see that
20:44	we have , uh , multiplication in two places and
20:47	we want to go left to right . Another way
20:49	to do this . It's really the same thing .
20:51	You can say eight times eight is 64 . Then
20:54	you just carry the rest of the problem minus nine
20:57	times to . So we just did the first multiplication
21:00	down below , and then in the very next step
21:02	. We see . Well , this is a subtraction
21:04	. We can't do that . We're gonna do this
21:06	multiplication . So 64 minus the nine times two becomes
21:10	the 18 , right ? And then we already figured
21:13	out that 64 minutes 18 is 46 . So that's
21:16	a way to break it down to even more steps
21:19	. Do the very first multiplication left to right .
21:22	Then you're scanning to the right . Then you do
21:23	that next multiplication because we're going to the right .
21:26	We do that one . And then the very last
21:27	thing we do that subtraction , notice , additions ,
21:30	subtractions always last in all of our problems , unless
21:33	and sits inside of parenthesis , that's the only exception
21:38	. All right , now , the next thing we
21:39	want to do just to gain some external practice is
21:43	what about four times eight plus 19 minus three .
21:49	What do we do first ? Well , the first
21:51	thing we do is we say way we have parentheses
21:53	, So we're going to do that now . Inside
21:55	the princes is subtraction . Now I've been saying subtraction
21:59	comes last , but the only exception , remember ,
22:01	is if it's inside of princes , then we can
22:02	do it First . We have to handle the princess
22:04	first . So 19 minus three . Um , if
22:08	you remember is 16 , so that becomes 16 .
22:11	Now , this stuff has to remain in the problem
22:14	untouched . The very first thing we do is we
22:16	handle the princes making the 16 . Now you can
22:19	keep the princes there , or you can drop them
22:21	. Either way . Once you've evaluated the parentheses ,
22:23	then the number you have is just going to carry
22:26	down through the problem . Now we've done the princes
22:28	. Now we look for multiplication and division left to
22:31	right . Now we see in the problem . There's
22:34	a plus here . We don't do that . First
22:36	we do this . Multiplication four times 8 32 plus
22:40	16 is just going to hang on for the ride
22:42	. And then what ? We have 32 plus 16
22:44	. The only thing left to do is the addition
22:46	48 this is the final answer . That's the final
22:50	answer . All right , now , so far we've
22:52	been doing problems , and they've been increasing complexity .
22:56	But here I want to do one last one just
22:58	to flex your muscles a little bit and give you
22:59	a little bit of extra practice . And this will
23:00	be our last problem for this lesson . And in
23:03	order to do that problem , I'm gonna go off
23:05	to the next board here . What if we have
23:07	parentheses ? 20 minus three times six , divided by
23:14	parentheses . Two times two minus three . So here's
23:19	a little more complicated because we have two sets of
23:21	parentheses , right ? They're linked by division . But
23:24	inside of each parentheses , we have a mixture of
23:27	addition subtraction in this case with multiplication , subtraction and
23:30	multiplication . So students sometimes look at that and they
23:33	don't know what to do . You just follow the
23:35	rules , step by step . So the first thing
23:37	is , you look and say , Well , I
23:39	have parentheses . I have to do what's inside of
23:41	these parentheses . First I have to . Right .
23:44	Once I'm inside of the parentheses , I still follow
23:46	the same rules . Add subtract first . I'm sorry
23:49	. Multiply and divide first , then add and subtract
23:52	Last . That's where I follow when I'm inside of
23:55	the parentheses . So when I'm working inside of the
23:57	parentheses , I'll carry it down with the princes like
24:00	this . I can't do this subtraction . First ,
24:02	I have to handle the multiplication first . So three
24:05	times six is 18 . I close that parentheses off
24:09	. So you see , I can't do it all
24:10	in one step . I have to do the multiplication
24:12	first because that comes first . Then the division carries
24:15	over inside of this parentheses . I look inside and
24:20	I say , Do I have multiplication or division ?
24:22	And I do . So I do . This first
24:24	two times two is four . Let me just carry
24:26	the minus three for the later step in the problem
24:29	. Mhm . Again . I'm still working inside of
24:31	these parentheses here because I have to follow the order
24:34	of operations inside of them . So what I have
24:36	here is 20 minus 18 . The only thing left
24:39	to do is to and then over here , uh
24:43	, four minus three , the only left to do
24:45	things left to do in there . So I have
24:47	to do it is one . So I have my
24:48	parentheses here . I'm free to drop these parentheses now
24:51	because they don't They don't serve any purpose to just
24:53	have to go around one number and two divided by
24:56	one is two . So the answer to this whole
24:58	entire thing is to now if you start doing crazy
25:01	things like six divided by two first like don't do
25:04	the prince these first , you're not gonna get the
25:05	right answer . So order of operations is one of
25:08	those things that trips up a lot of students .
25:10	But once you understand the rules , every problem can
25:13	be broken down into very , very similar things .
25:16	The very first thing we want to always do is
25:20	do the inside of the parentheses first . And I
25:22	think by now you've seen that once we get inside
25:25	the parentheses , we still have to follow , multiply
25:27	and divide first and subtract . Secondly , even inside
25:30	the parentheses , right ? But first we look for
25:33	Princess . Then outside of that , we do multiplication
25:36	division left to right first , then adding and subtracting
25:39	left to right and my left to right . I
25:41	mean , literally , you have to go , like
25:42	in this problem . Um , like in this one
25:45	right here . We had a whole string of divisions
25:47	and multiplication on the same level . The way you
25:50	evaluate it is do the first one . Then do
25:52	the second one . Then do the last one you
25:54	read , like reading a book left to right .
25:56	So make sure you understand these guys watch all of
25:59	these again . Practice every one of these problems again
26:01	. So you feel like you're doing pretty well and
26:04	then go off into the worksheets . Solve all of
26:06	those Get your skills really , really sharp with this
26:09	, because order of operations comes up a great deal
26:12	in math , so you want to make sure you
26:13	really and truly are good at it . The good
26:15	news is , once you understand it , you can
26:17	get all of these problems and questions correct . And
26:20	so it's just something you have to practice , so
26:21	make sure you go get that practice right now .

Summarizer

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This is just a few minutes of a complete course. Get all lessons & more subjects at: http://www.MathTutorDVD.comâ. This lesson teaches how to use the rules of order of operations to solve problems.

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01 - Learn Order Of Operations (5th Grade Math) is a free educational video by Lumos Learning.

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