Lesson video

Hello everyone.

And welcome to today's lesson.

In today's lesson, we're going to be looking at how we subtract when we're subtracting from a multiple of 1000.

If you can, can you please make sure that you've turned off all notifications on your phone tablet or whatever device you're using to access today's lesson on.

Don't worry about getting equipment just yet.

And we'll go through all of the equipment that we need in a moment.

But please try and find someone nice and quiet in your home so that we're not going to be disturbed during today's lesson.

When you're ready, let's begin.

Okay then, let's run through today's lesson agenda.

We're going to just start off by using the column method.

We're going to see how it works using the column method, and if it's a great method or not to use, when we're subtracting from a multiple of 1000.

Then we're going to think about, and let's explore.

You're going to have a go and this time you're going to tell me what would you do? Then we're going to look at more efficient methods.

So what's going to be the best strategy if we're given a question when we're subtracting from a multiple of 1000.

And then finally it will be time for you to do your independent task, which will be create an equation.

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

So please pause the video now, go and get those things.

If you haven't got them already.

Okay, welcome back.

Let's get started.

So my equation today is 7,000 subtract 4,726.

What do you notice about the equation? Yeah, especially the whole.

You look up our model, You can see the whole here.

Well, I notice that it's a multiple of a thousand and I know that if I'm subtracting my part and the numbers are my parts are greater than the numbers that are in my whole in each column.

And I'm going to need to do some regrouping.

So just to hint this tells me I've got a lot of regrouping today.

We're going to re-group from each of these three columns from my hundreds, all the way to my ones.

So what method should we use? Should we try the column method and see what happens? Do you think it's going to be efficient? What do you think will happen if I do use it? Let's find out.

So I'm thinking, Ooh, I think we should use the column method because it's going to require multiple regrouping and I know how to do that.

Let's see what it looks like on our place value grid then.

I'm covering the ones column.

This is the ones column here.

Here's my number, here's 7,000.

These columns are empty because there are place value that they told us that are in them.

There's the zeros in them.

Because my numbers are multiple of a thousands.

So how am I going to start off? Cause I've got nothing to take away from my six.

I've got nothing to take away from my two.

And I've got nothing to take away from my seven.

So I'm going to have to regroup all the way from my thousands and work it through, before I can subtract, sorry, my one's column.

So I'm going to need to take one of my thousands leaving with 6,000.

To regroup 1000 here and see, this is 6,000 to 10 hundreds here they are.

Now, can I do zero subtract six stuff.

I can't, I need to do some more regrouping.

I need to take one of my hundreds and I need to regroup it so that I'm remaining with nine.

So here are my nine.

And I'm going to give myself ten tens.

Here is my nine hundreds and here are my ten tens.

Can I do this ones column here? No I can't, so I need to regroup again.

I need to take one of my tens.

It's going to leave me with nine tens here and 10 one's here.

Pardon me, and ten ones here.

So I've now created a number that I can actually subtract from.

So I can do 10, take away six, and it's going to leave me with four.

Then I can put four in here.

Now, if I do nine tens, take away two tens.

I can absolutely.

It's going to give me seven tens.

So I'm going to put my seven tens in here.

I have now gotten nine hundreds and I take seven away from my nine hundreds, like, huh, this going to leave me with two.

And finally I have 6,000 and I want to take away 4,000.

I do that, I can.

It's going to give me two.

My new number is 2,274.

There's my answer.

I can put it in there.

Now, what's that an efficient strategy? Did that take me a long time and require a lot of regrouping and thinking really carefully about which column I was regrouping and how many I was regrouping.

Absolutely it did.

It was quite complicated just to even show you on our place, value, counters, how it needed to look, to be able to show you how I was going to regroup it.

Let alone looking over here.

It can become quite complicated.

So what I want you to do for today is let's explore.

It's your turn today.

Have a think for me about how you would calculate this answer.

Are there any other methods you could use? What would you do? So what I want you to do is pause the video and have a go using a method that you would use to answer this equation.

Then we're going to think about the different methods you could choose to use.

So I'm going to hide myself for a moment.

Please pause the video now and have a look at how you would calculate the answer to the following equation.

What methods would you use? Okay, welcome back.

Let's see then.

So other methods that we could use.

We could choose to partition our part.

We know this is as a whole.

We could partition our part.

We could use a number line to help us do that.

We could, maybe we could count on our number line.

Yeah, so I could count on, it could be using a number line.

It might not be using a number line.

Was there any other method that you could think of? What we're going to do now is we're going to look at how we would count on the same equation, but using a number line.

So I'm going to put the number 4,726 here on my number line.

I'm going to count on using my number line to help me.

I'm going to add four, to take me to the next multiple of 10, 4730.

Now I want to get up to the next multiple of 100.

So I need to make a jump at 70 to take me to 4,800.

Now I want to go the next multiple of a thousand, it's going to make me jump to 200 to get me to 5,000.

Then I'm going to do one big jump off 2000 to get me to 7,000.

So, what do I need to do to be able to work out this answer? I need to recombine and I need to add those four numbers together.

2000 + 200+ 70+ 7 = 2274.

Not 24.

What do you notice about how long and how complicated that was in comparison to the column method that we used earlier? Absolutely, it was much quicker.

There was no one near as much room for error using this method.

And I didn't have to think nine regrouping again.

It was just so much more straight forward.

So when we're multiplying, when we are multiplying, talking about multiplying? When we are subtracting from a multiple, I think that was what I was going for.

A multiple of a thousand, sometimes counting on can be much quicker.

It's a much weaker method in that case, it didn't require a grouping.

It just required recombining at the end.

Could we partition and subtracted that using a different method? So let's see same equation.

I'm only going to partition part, not the whole.

So, I'm going to partition my part into 4000,700,20,6.

Now to do that, I take my whole, I take my 7,000 and I subtract my 4,000 to give me 3000.

Using my 3000, I subtract 700 to give me 2,300.

Using my 2,300, I subtract 20, give me 2,280.

\ Using 2,280, I'm going to subtract six to give me 2,274.

Again, a really efficient method, really straightforward.

I'll be using partition and subtract or count on the number line, but both much more efficient methods than using the column method, in the case of multiples of thousand.

Now that doesn't mean that you have to use partitions and subtract, or you have to use count on the number line.

It can just be a personal choice because both of them are efficient.

They're more efficient than using the column method.

If I was to use the column method, then there's much more room for error.

As we saw, it can be quite complicated and time consuming.

While these methods aren't going to be as time consuming and they're going to be more accurate at getting us that correct answer.

So what I'd like you to do now is if you feel confident, pause the screen now.

So have I got a new equation, which is 5,000 subtract 1,254.

Would you use the column method? Try not to use the column method, think about using either partitioning, a number line or using counting on to help you here.

You're not feeling so confident.

Don't worry.

Let's have a look at how we can find the difference together.

So remembering that counting on this one.

Well, here's my equation and I'm going to partition the part today.

So I'm going to partition 1,254 into 1000,200,50,4.

Now I'm going to take my original number 5,000 my whole.

I'm going to take away a thousand, 4,000.

Now I'm going to take away 200 which gives me, 3,800.

Now I'm going to to take my 50, which gives me 3,750.

Now I'm going to take my four which gives me 3,746.

My answer therefore, I'll get rid of that.

My answer therefore is 3,746.

Much, much quicker than using the column method.

You could if you wanted to, use that number line to help you, either of those two methods are efficient.

So it's now going to be time for your independent tasks, subtracting from multiples of 1000.

So I'm going to hide myself so you can see clearly.

What I'd like you to do today is, you have some digit cards here.

I'd like you to arrange the digits into the digit card, sorry, into the boxes above to create an equation, calculate the difference, using an efficient strategy.

Now I've got a bit of a challenge to you today.

I'd like you to try and find the greatest possible difference, the smallest possible difference, and differences even, and a difference that's odd.

Don't worry if you're finding that part a bit tricky, you can still do the main part of it, the task, which is here.

Pause the video now to complete your task.

Don't forget to resume it once we've finished and we're going to go through the challenge all together.

Okay, welcome back.

You can see me again now.

So we're going to go through the answers to the challenge part today.

Because there's lots and lots of different equations that you could have made using the multiples of a thousand other digit cards here.

So the greatest possible difference is the first one that I've made.

So I've made the equation 9,000 subtract 2,578 to give me the greatest possible difference, which is 6,422.

The smallest possible difference.

I've used the digit card eight and then 7,952 to give me a smallest difference of 48.

Now we're looking at an even difference and odd difference.

Now I know that if I want to create an even difference, I need to put an even number in my ones column.

So I made the number 5,000 subtract 2,978.

Give me the answer 2022.

Now I know it has to be an even number in my one's column to give me an even difference.

What's it going to be if I need to find an odd difference? Absolutely.

I need to put an odd number into my ones so that I get odd difference here.

5,000 subtract 2,877.

70? wrong step, definitely not 70.

97 is equal to 2103, there we go.

There's an odd number here.

If you'd like to, please ask your parent or carer to share your work from today on Twitter, by tagging @OakNational and using the hashtag, LearnwithOak.

Great work today.

I've been really impressed.

There's multiples of 1000 can be really tricky unless we have a really efficient strategy to deal with them.

So what I'd like you to do now please, is complete the quiz and show off all of your fantastic learning from today.

Don't forget to come and join us again soon for some more fun maths lessons.

Thank you very much.

Hopefully I'll see you soon and goodbye.