# Lesson video

In progress...

Hello again, everyone and welcome back.

Before we start our lesson today on multiplying and dividing by 10, 100 and 1000 within a context, just wanted to start off with a little joke for us, so here we go.

What happens to the frog who parked on double yellow lines? Not sure, he got towed away.

No, wrong nevermind.

Okay, on with the lesson then.

So, let's have a look at today's agenda before we do anything else.

So, making sure that first off, we're going to revisit multiplying and dividing by 10, 100 and 1000.

We're going to have a look at putting that into context of some problems and word problems that may going to have a go at doing that in our independent task.

Now, making sure that you've got your pencil and your piece of paper, cause that you can make jottings and do any work you need to, as we go through.

Before you start with multiplying and dividing by 10,100 and 1000 it's a really useful representation or support documents have to have yourself a place value chart.

So, if you don't have one already, you might want just to draw one on a piece of paper, or if you've got a whiteboard even better, it's just going to be really useful for today's lesson.

So, to revisit some of the things that we've done before, we're going to have look at multiplying by 10, 100 and 1000 first.

So, we're just going to review it slightly.

So, just remembering that we multiply by 10, 100, 1000 were making the number greater.

So, we're multiplying by 10 we are making each digit within that number 10 times greater.

So, that is why we move one space to the left.

Multiplied by 100 we're making it 10, 100 times greater.

Therefore we move two places to the left and then 1000 we're making it 10, 100, 1000 times greater, so each digit is going to become a thousand times greater, therefore we move each digit three places to the left.

Okay, so just a bit over view feedback.

So, I'm going to give us a number.

7.

So, what I'd like you to do is to multiply this number first by 10, then multiply the number by 1000.

Sorry, then multiply the number by 100, then multiply it by 1000.

So, you should have three different numbers then.

Okay, so pause the video and have a go at that and then we'll come back and see how we did it.

Okay, so let's have a look then 43.

7 starting off we want to multiply it by 10.

So, we know that each digit is going to become 10 times greater.

So, move one space to the left.

So, you should have 437.

Okay, so you can see that each digit has moved one space to the left and got 10 times greater.

Now, next, I want to multiply 43.

7 by 100.

So, this time we need to move each digit, two places to the left.

Each digit needs to get 100 times greater.

So, we should have 4,370 remembering we then need to put our placeholder, okay.

So, making sure that we have our placeholder there to note that there aren't any ones, but we do have 4,300 and seven tens.

And then we need to multiply 43.

7 by 1000.

So, make sure we move each digit three places to the left, make each digit 1000 times greater.

So, we shouldn't have any at the path and amount 43,000 seven and then remembering our placeholders 700.

So 43,700.

Okay, so well done if we did that was just, it's a bit of a review of our multiplying by 10, 100 and 1000.

Now, dividing by 10, 100 and 1000 very similar in terms of the way we're structuring it and solving our problems. But remembering that we're moving to the right, because we want each digit to become smaller.

So when we multiply, if we divide by 10 we're going to be making each digit 10 times smaller.

Divide by 100 we're making each digit hundred times smaller.

So 10, 1000 times smaller, so that's two spaces.

And if we divide by 1000, it's going to be move three places cause we're making it 10, 100, 1000 times smaller.

Okay, so again, I'm going to give us a number to start off.

Okay, so pause the video now, and I want you to come up to divide it by 10, 100 and 1000 and come up with three new numbers and play when you're ready.

Okay, so let's have a look at how we did well.

First off, let's divide it by N, so you can see that my four in my 10 000 has gone to the 4,000.

Then I've got my 3000 now divided by 10 to be 300.

My 400 has become the 40.

And my three tenth become three ones.

Okay, so I'm left with 4,343.

Now, I want to divide this original number that I've got here by 100.

So, this time we're moving two places to the right we're dividing it by hundreds.

So, it should have 430.

I should have four ones.

I could have a decimal place and three tenths.

Okay, so hopefully we're happy with that and we feel like we've got the right answer there.

So, moving on slightly, let's go into other 1000 now.

So, we want to divide by 1000.

So, this time we're going to have a four tenth.

You're going to have three ones have a decimal place then we'll have the four-tenths and we'll have three hundredths.

Okay, so 43.

43.

Okay, hopefully, we're starting to see some sort of pattern there emerging and were able to use that to support us slightly, but really important that we're able to explain why we're doing this instead of just following blindly, what we can start to see emerging.

We need to explain why we're doing it that's going to help us in a second when we come to solving problems in context.

So, just to make sure that we're familiar with this, I'm going to pause the video and have a go at solving some of these problems. We'll have a look at the answers and then we'll go into some problems in context.

Okay, let's have a look at our answers then so, 5.

6 multiplied by 100 is equal to 560.

6.

078 multiplied by 1000 is equal to 6,078 and 56.

89 divided by 10 is equal to 5.

689.

0.

66 divided by 10 is equal to 0.

066.

67.

36.

multiplied by a hundred is equal 6,736.

And lastly 0.

105 multiplied by 10 is equal to 1.

05.

Well done if you've got all of those.

Now, we're going to have a go at multiplying and dividing into some context.

Now, first off to get us thinking a little bit, just thinking how many grammes are there in one kilogramme? And how would you write one gramme in kilogrammes? And what could you use in order to be able to help you? How a bit of a thing, what could you use? What knowledge could you use in order to support you with that? Hopefully, way would say that there are 1000 grammes in one kilogramme, and that if we wanted to write our grammes now, well, we need to know that 1000 grammes is equal to one kilogramme.

So, that's going to help us in order to be able to fall and solve our problems. So, using our understanding of that, and you'll see that I put a nice little chart here in order to just to remind us and support us slightly.

These bananas have a mass of 200 grammes.

So, how would we write that in kilogrammes? What would you use to support us? What understanding might we use? We know that there are 1000 grammes in one kilogramme, so could we use this to help us? So, pause the video now and have a bit of think about how you might go about solving this.

Okay, so we've, we know that there's 200 grammes, but we know that there are 1000 grammes of crown.

We know that we're going to have to turn it into kilogrammes we need to divide by 1000.

So first off, I've got 200 grammes here and I want to divide it by 1000.

So, start off making the remember divide by 1000 means I need to move three places to the right cause I'm divided by 10, 100, 100 three places.

So, one, two, three.

So, I'm left with two and then nice and easy for the rest, really, because I don't need to put them out they're zero and they have no value.

So, I'm left with 0.

2 kilogrammes.

So, a massive bananas is 200 grammes, which is equal to 0.

2 kilogrammes.

Now, another problem for you have a look at.

Here I've got two different animals.

Now, the male lion has been measured in grammes, but we want to know what his mass is in kilogrammes.

And the ego out has been weighed in kilogrammes, but we want to know what the mass is in grammes.

So, think about how we might be able to use our knowledge.

And going up here to help us to be able to tell us the male lion, their mass in kilogrammes, and the owls mass in grammes, okay.

So, pause the video now, then when you're happy, play the video and we'll have a look.

Okay, so hopefully we're happy with that.

So, we know that this is the grammes at the moment, so we know we're going to make it kilogrammes then to get from grammes to kilogrammes, we need to divide by 1000.

So, in order to find his mass and kilogrammes, we need to divide by 1000.

We should have found 195 kilogrammes.

Now, our owl we know at the moment it's kilogrammes, but we want it in grammes, so we need to multiply by 1000.

So, 2.

65 multiplied by 1000 is equal to 2,650 grammes.

Okay, so well done if you're doing this, we using our knowledge of multiplying and dividing, to help us to solve some problems in a context.

Now, something you may be more familiar with if you've been in a shop and you've to use some money, but how many pennies are equal to £1.

What? Yeah, okay, £1 is equal to 100 pen for 100 pennies.

So, that piece of information is going to help us to solve some problems as well.

Remembering, I would say that the game we had it for the problems with kilogrammes, that little chart is going to help you to just remember what you've got to be doing each time to solve the problems. So, if I've got £1.

56, what would that be in pence? To thinking about our chart that we've got, we would have to, if I've got it impounds at the moment I want into pence, I need to multiply by 100.

So, I've got £1.

56 and if I multiply by 100? I know that I need to move two places to the left.

I need to make it 10, 100 times greater.

So, in that case I'm going to have one is going to go to my hundreds.

I'm going to have one.

So, we're going to have five I'm not going to have my six, 10, six hundreds here it's going to go to my ones.

So, I'm left with 156 pence, right.

So, £1.

56 is equal to 156 pence.

Well done if you got that.

Now, I want to give you a bit of practise on this, so I'm going to give you a little bit of time.

So, pause the video, remember a little chart there to help you to solve this problem.

Can you solve these conversion problems? Okay, pause the video now and then when you're ready, play again.

Let's have a look at our answers then.

So, two £2.

35.

Well, what do we need to do to that? We need to multiply it from pounds to pence.

We need to multiply by one hundreds.

We should have got through 235 pence.

45 pence in pounds we need to divide by 100.

So, you should have got 0.

45.

And then £10.

56 into pence will we need to make it to get from pounds to pence.

We need to multiply by 100.

We should have got 1056 pence, and then £0.

67.

We need to send it to pence would be 67 pence need to multiply 100.

And 506 pence in pounds we need to divide by 100 to give us £5.

67.

Okay, what I'd like you to do now is to go to your work independent tasks.

So pause the video now, complete the worksheet, and then come back here and we'll go through some of the answers for the task.

Okay, hopefully, you've finished that now.

Let's have a look at one our answers.

The question one, converting mass into the desired units.

So, we want to snow the chimpanzees body mass in grammes when it was currently in kilogrammes.

So, you had to use that conversion between grammes and kilogrammes.

We needed to multiply it by 1000 kilogrammes, we should have got 60,000 grammes.

And then the cheetah's mass was in grammes currently, but we wanted it in kilogrammes.

So, we'll need to divide by 1000.

So, 45,000 divided by 1000 is equal to 45 kilogrammes.

Well done if you did that.

Question two, we convert the mass.

So, from pounds depends something we practised earlier in the lesson, so hopefully you're confident with this.

You should have got 456 pence.

£672 and 2,467 pence.

Well, if we've got those.

Now, bit of a thinker who spent more money? Now, you could have converted either way in order to help you to solve this problem.

I'm going to show you both.

So, what we could have done is we may have changed the pound into the pence and said, well, he's obviously got 275 pence, or we could have changed 280 pence and converted that into pounds give us £2.

80, either one way we should be out at the tower who spent more money.

We can see that the boy in green spent more money spend about 2.

80 or 208 depends as opposed to 275 or £2.

75.

And the question four.

Stack of paper containing 100 sheets.

And each stack can cost £24.

How much does each sheet of paper cost if there are 100 of them and the £24 total, we need to divide by 100 to work out what the cost of each one might be.

So, if I get £24 and I divide it by 100, I should be left with 0.

24.

So, £0.

24.

And if I want to then change them to pence to make it slightly easier, you may have been converted that to pence to find that it was actually 24 pence.

Well done, if you're able to solve that.

And as I say, make sure you keep using that place value chart to support you and keep using that language and reasoning to always explain how, you know, your the answer is what you've got, okay.

So, well done with all of that as always, to do if you want to ask some of your work, make sure you ask your parent or your carer first, but you can share on our Twitter page.

Thank you very much for your time today.

It was really good have you hope you enjoyed the lesson and hope to see you again soon? Make sure you complete that and the blessing quiz afterwards, just to review your understanding, okay.

Thanks a lot, guys take care, bye-bye.