Lesson video

Hi everyone, thank you for joining me.

My name is Ms. Jeremy and today's math lesson is focused on rounding five digit numbers to the nearest multiples of 100, 1000 and 10,000.

So get yourself sorted with a nice quiet space, free from distractions and when you're ready press play to start the lesson.

Let's start by looking at our lesson agenda for today.

So we're going to begin with a warm up.

We'll be rounding to the nearest 10,000 and 1000.

Then in our new learning we'll be rounding to the nearest 100 and later on, we will be doing some mixed rounding before our independent task and quiz at the end of the lesson.

For today's lesson, you will need a pencil and some paper.

So make sure you pause the lesson here and find those things.

And once you're ready, you start the video ready for the next part of you lesson.

All right, let's get started with our warm up.

Our warm up question says this.

How would we round this number to the nearest 10,000 and the nearest 1000? So we have the number 54,532.

And our challenge is to try and round this to the nearest 10,000 first.

I'm going to give you five seconds to think about your strategy.

What will we need to do in order to round to the nearest 10,000? So, the first thing that I need to think about is what my nearest multiples of 10,000 are for this number.

So the number is 54,532 and the digit in the 10 thousands places this five.

So I'm thinking about my closest multiples of 10,000.

Here on this side, I think that's going to be 50,000.

And then my larger multiple of 10,000 on the other side is going to be 60,000.

My job is to work out with the 54,532 is closer to 50,000, or it's closer to 60,000.

The way I'm going to do that is to pop in my halfway point as well.

So my halfway point is 55,000.

And I know if this number that I'm rounding goes beyond, is greater than 55,000 then we're rounding up.

If the number is less than 55,000, we'll be rounding down.

So let's have a look.

I can see that 51,000 would be here, 52,000, 53,000, 54,000.

So 54,532, I'm placing around here.

And you can see that even though it's close to the halfway point, it's not quite that, therefore it rounds down to 50,000.

So in rounding to the nearest 10,000, we round to 50,000.

Now I've got to think about rounding to the 1000.

Again, I'm going to give you five seconds to think about the strategy that you would use to round this number to the nearest multiple of 1000.

Okay, so this is the strategy that I would use, let's see if it's the same one as yours.

I need to do the same thing again, but this time I'm focusing on that digit, that is in the one thousands place.

We are looking at the four, which is equivalent to 4,000.

So I need to work out with my smaller multiple of 1000 is, and my larger multiple of 1000 is.

My smaller multiple of 1000 is 54,000 and I'm placing it just here at the end.

My larger multiple of 1000 is 55,000 and I'll place it on this side here.

Once again, my job is to work out whether 54,532 is closer to 54,000 or 55,000.

I want you to have a guess before I actually calculate this.

Do you think this number is going to round up to 55,000 or down to 54,000? Okay, let me put my halfway point in to help me out.

So I know that halfway between these numbers, I've got 54,500.

And my job is to place 54,532, which is actually very, very close to where my halfway point is.

It's just here.

But, it goes over that halfway point.

So in this case, 54,532 rounds up to 55,000.

Okay, so let's move on to our main part of our lesson, where are we going to be rounding to the nearest multiple of 100.

We've already had a practise of around five digit numbers to the nearest multiples of 10,000 and 1000.

And the steps to success for rounding to the nearest multiple of 100 is actually relatively similar.

We're just looking at different multiples.

So let's get started with a little example.

I've got the number 74,823.

And I'd like to round this to the nearest multiple of 100.

So in this particular case, I'm focusing on that digit, that's in the 100 column.

I'm looking at whether that is going to be rounding down or up.

The first thing I need to do is identify the closest smaller multiple of 100.

And I can see in this case, it's going to be 74,800.

So I'm going to put that the end of my number line.

I want to count 100 up to get to the larger multiple, the closest larger multiple and in this case, it's 74,900.

The next thing I need to do is find the halfway point.

The halfway point will help me out because if the number that I'm rounding is greater than the halfway point, I'll be rounding up.

If it's less than halfway point, I'll be mounting down.

So my halfway point for, this particular number line here is 74,850.

And I can see straight away the 74,823, is going to be placed, well, let me work it out.

This would be 74,810.

This would be 74,820.

So I'm going to place 74,823 around here.

And immediately you can see that it's far closer to my smaller multiple 74,800 than it is to my larger multiple 74,900.

So in this case, my number rounds down.

And I can say the 74,823 is approximately equal to, remember this approximately sign, 74,800 when rounded to the nearest multiple of 100, which is what we're doing here.

So you can see the same success criteria that we've used in the past is applicable for this particular type of question as well.

So I'd like you to have a little go as well.

We're going to use the number 56,399.

And what I'd like you to do is to use the same strategy to identify what that would be, if we were rounding to the nearest multiple of 100.

Pause the video to complete your task and resume once you're ready and we'll look at the answers together.

Okay, how did you get on? Let's look look at the answers together to this particular question.

So remember we're rounding to the nearest multiple of 100.

So I'm looking at that digit that's in the 100 column, which at the moment is a three, that's equivalent to 300.

The first thing I need to do is identify, the closest smaller multiple.

I need to work out what the smaller multiple of 100 is in this case.

And I can see that for this particular example, it's 56,300, so I'm going to put that in the end here.

I've now got to think about the closest larger multiple, and I'm counting on 100 more in this case, it's 56,400.

And I need to put in my midway point, my halfway point, because that will help me determine whether I'm rounding up or down.

So in this case, my halfway point is 56,350.

That's exactly halfway between, 56,300 and 56,400.

So now I'm going to place my number and I can see straight away that it's going to be way, way greater than my midway point, my halfway points.

Because this isn't 56,350, it's 56,389.

So let's come up with ways to find out exactly where that would be.

This would be 56,360, 56,370, 56,380 so I'm going to place 56,389 around here.

Which as you can see, it's much closer to 56,400 than it is to 56,300.

So using that approximately sign again, I'll do that there 56,389 is approximately equal to 56,400.

And it's important to mention when rounded to the nearest multiple of 100.

Okay, so now that we've practised rounding to the nearest multiple of 100, we're going to try a little bit of mixed rounding.

This is when we take one number and we round it to the nearest 10,000, the nearest 1000, the nearest 100.

And actually I'm going to try and use the same number line to do this today.

But what you'll notice is that I'm going to change those multiples, that smaller multiple at the end and the larger multiple at the other end.

And that will need to be changed depending on what time rounding to.

So our number is that five digit number on the screen.

I'd like us to say it together after three, one, two, three, 56,329.

And we're going to start by rounding it to the nearest multiple of 10,000.

So remember again, I'm looking, thinking back to that success criteria, I'm focused on that digit that's in the 10 thousands place currently.

The first thing I need to do, if I remember back to my success criteria is identify the smaller multiple of 10,000.

And in this case, we're looking at 50,000 counting 10,000 down to get to the larger multiple, which is 60,000.

And I'm thinking about that midway point.

What is halfway between 50,000 and 60,000? Have you got it? It's 55,000.

So we've got a workout is 56,329 greater than 55,000 or less than 55,000.

Well, in this case, you'll probably have spotted it's greater than 55,000.

So therefore this number when rounded to the nearest multiple of 10,000, rounds up to 60,000.

So what going to do, is just write this in a little bracket here.

I'm going to write that around up to 60,000 so I can remind myself when I think back to it.

Okay, so now we're going to have a look at part two of our question.

We're going to have again rounding, 56,329 to the nearest 1000.

So we're going to have to change our smaller multiple, and our larger multiple, and our halfway point.

This time I'm focused on the digit, which is in the thousands place, which is that? Six.

Which is equivalent to 6,000.

So this time my smaller multiple is 56,000.

My larger multiple is 57,000.

And what will my midway points be? My midway point is 56,500.

So I would like us to play 56,329 on our number line to work out whether which multiple is closest to.

I'd like you to take your finger and place it on the screen where you think I'm going to be placing my point.

And let's see if we're the same.

So here I go, I'm going to have a look.

56,100 would be here, 56,200 would be here, 56,300 would be here, so I'm going to place it around there.

And as you can see, we are going to be rounding down in this case.

So 56,329 rounds down to 56,000, when rounding to the nearest multiple of 1000.

Okay, last thing for us to have a go at doing, I'm just going to rub out our markings, so we've got a nice, clear, a number line to work with.

And we're going to focus on rounding to the nearest 100 now.

So I'm focused again on that one hundreds column.

I'm looking at that hundreds and I'm going to need to change my multiples to see what they are now.

So my smaller multiple will be 56,300.

My large multiple will be 56,400.

My midway point it's 56,350.

Let's see where I'm going to place 56,329.

Take out your finger, pop it on the screen where you think it's going to go.

So I'm going to place 56,329 around here.

And you can see quite clearly here, it's going to round down again.

So this time it rounds down to 56,300, and then you can see that we've got three very different answers, depending on what we're rounding to.

Last answer, the third answer that we gave is the most specific, the closest to our original answer, and because we rounding to the nearest multiple of 100.

Whereas the first answer we gave, was rounding to the nearest multiple of 10,000, so our answer is far further away from our original number.

But you can see how we can use the same number line, changing those multiples to help us out as we go.

So I'd like you to have a little go now.

I would like you to have a go rounding the number, 45,200 to the nearest multiple of 10,000, then to the nearest multiple of 1000, then to the nearest multiple of 100.

Pause the video to complete this task and resume it once you're finished.

Okay, how did you get on? Let's have a look at some of the answers.

So when you around this to the nearest multiple of 10,000, 1000, 100, you might've noticed that you will have needed to change your smaller multiple, large multiple, and halfway point each time.

The answers are as follows.

Rounding to the nearest 10,000, the answer was 50,000.

Your number rounded up.

Rounding to the nearest 1000, we actually rounded down in this case, and the answer was 45,000.

And rounding to the nearest 100, or we didn't actually have to do anything.

It was already kind of that, ours was 45,200, which was the same as our original question.

How did you get on with those? Let's see what our next task is.

So you can also have a look at problems related to rounding with regards word problems. So let's have a look at this problem.

It says during the Olympic games, 76,452 people attended the running event.

And it asks us approximately how many people attended? What I'd like you to do is to have a think about what you think we should round this number to.

Should we bound to the nearest 10,000, to the nearest 1000 or to the nearest 100.

And why? Well, actually, any answer is correct in this case, you can amount to any of those possibilities.

However, if you want a more specific answer that is closer to the original number, you should round to the nearest multiple of 100.

If you actually would like a broader answer that isn't necessarily as close to your original number, then you should round to the nearest multiple of 10,000.

Which is what I'm going to do.

I'm going to say 76,452, which is the number of people that attended precisely, is actually approximately equal to, and I'm going to use my approximately sign.

Is approximately equal to 80,000 people.

Because I've rounded that to the nearest multiple of 10,000.

And actually that number 80,000 is much easier for me to use, to calculate with, to speak about and that's much easier for me to use than 76,452.

So rounding to the nearest multiple of 10,000 worked for me that.

If you decided to round to the nearest multiple of 1000 or 100, that's also absolutely fine.

So you can see how we could use rounding in the context of word problems as well.

So moving on to your independent task, but today you've got two questions where I'd like you to demonstrate the smaller multiple, the larger multiple and the rounded answer, for different values.

And then questions three and four, you're going to be rounding those numbers to the nearest multiple of 100, 1000 and 10,000.

Let me demonstrate one for you so you can see what you're going to be doing.

So question one says 5,462 people went to the velodrome.

And what we're going to try and do is round 5,462 to the nearest multiple of 100 to begin with.

So the first thing I'm going to do is try and find my smaller multiple of 100.

My smaller multiples of 100, 1000, 10,000 are going to go in this column here.

And my large multiples are going to go up here.

And then my answers are going to go here.

This is just like a number line almost, but we're doing it on a table instead.

So I can see that my smaller multiple of 100 in this case would be 5,400.

Counting at 100, I can see my larger multiple be 5,500.

And I've got to work out, it's 5,462 closer 5,400 or 5,500.

Well, I can see in this case, it's closer to 5,500.

So my answer is 5,500.

And you can see, I'm just adding that in there.

For your next particular question here.

We're dealing with the same number, but this time we're rounding to the nearest multiple of 1000.

So you've got to think about your thousands in this case.

I'd like you to complete this, on a grid, just like you can see here.

And for questions three and four, you can complete separately.

You're going to round those two numbers to the nearest multiple of 100, 1000 and 10,000.

It doesn't matter the order that you do this in.

Pause your video now to complete your task.

And then don't forget to come back to have a look at the answers together.

Okay, let's have a look at our answers together.

So what I've done is I've put the answers here for our different rounding questions.

You can see that when we're rounding 5,462 to the nearest 100, 1000 and 10,000, we get very different answers.

And you can see they're written just there for you.

And then when we're rounding 17,354 to the nearest 100, 1000 and 10,000 you can see the answers on the right there.

Spent a bit of time now marking your answers to check whether you got the same as me.

And the last questions that you completed on the screen here as well.

I have started with on the left, they're rounding it to the nearest 100, then to the nearest 1000, then to the nearest 10,000.

Spend some time marking your answers for these as well.

Okay, that's good, we've come to the end of our lesson, where we were looking at rounding five digit numbers to the nearest multiples of 100, 1000 to 10,000.

Well done for all of your hard work today.

If you'd like to please ask your parent or Carer to share your work on Twitter, tagging @OakNational and hashtag LearnwithOak.

The only thing that's left to do today is to complete your quiz.

Thank you for joining me for lesson in math today.

It's been great to have you, do come and join us for some more math lessons again soon.

Bye.