Lesson video

Hello, everybody, how are you? My name's Miss Brinkworth and I'll be doing today's maths lesson with you which is to multiply two-digit numbers by six using partitioning method.

So, all you need for today's lesson is a pen and pencil and something to write on.

If you can find, online, some Dienes, Dienes are the little blocks that you put together, you've probably used them at school and there are some great online tools you can use.

If you can find some online ones, they may help you with today's lesson.

So if you need to pause the video here and have a look for them, as well as getting your pen and paper together, do that now.

If you can't find any online Dienes, please don't worry, you'll be absolutely fine with today's lesson.

Okay, what I'm going to do is say the star words and if you could say them at home that will really help.

So we've got multiplication, regroup, partition, factor, commutative, times, equal parts, column addition.

Now you've probably heard a lot of these vocabulary before, it's the vocabulary we often use when we're talking about multiplication in terms of time, multiplication.

We talk about the commutativity between division and multiplication and how those two are the inverse relationship.

We're also going to use column addition today as we're moving onto multiplying bigger numbers.

So let me show you what I mean by that.

The first thing is to partition.

I'm sure this will just be revision for you, but it's really important that in today's lesson we are partitioning two-digit numbers accurately.

So what we mean by that is just splitting our two-digit numbers into tens and ones.

So 12, for example, splits into 10 and two.

Can you pause the video here and just split those other four numbers, partition them into their tens and ones please.

I'm sure this was quite easy for you, but it's really important to do this accurately, so let's just see how you got on.

So, 54 is 50 and four, 76 is 70 and six, 37 is 30 and seven, and there we go, and 99 is 90 and nine.

So it's going to be really important to do that really well today.

Another skill that's going to be important today is to times by 10.

So, if we just have a look at that example there, when we times by 10 we're making something 10 times bigger, so each digit moves one decimal place to the left and we put that zero in as a placeholder if we need to.

So in that example, 21 times by 10, the two moves from the tens column into the hundreds, the one moves from the ones column into the tens, and then we use that zero as a place holder so that 21 times by 10 is 210.

Pause the video here and have a go at those other five please.

Well done, again, I'm sure this is just revision for you, but it's a really important skill to get some accurate questions answered today.

So, six times by 10, 60, 10 times by 10 is 100, 80 times by 10 is 800, 14 times by 10 is 140, and 21 times by 10, we've done that one, 210, well done.

Okay, so here's our learning objective, let's just pick it apart a little bit and make sure we understand everything that it says.

So we are multiplying two-digit numbers by six using partitioning.

So, two-digit numbers, we've talked about these already, but they are numbers like these, 12, and 67, and 34, which have a number in both the tens and the ones, two-digit numbers, that's what we're going to be looking at today, just two-digit numbers.

Hopefully your six times table is one that you're quite familiar with, but there it is to just remind you.

And then we're going to be using partitioning and we've talked about that a little as well, 16 partitions into 10 and six.

Along with multiplying by 10, this is all the information that you need for today, we're just going to pull it all together so that we can multiply two-digit numbers by six.

Okay, so for example, 14 times by six, what does this look like? So the first thing we need to do is partition our two digit number, so 14 partitions into 10 and four.

Then we multiply each of those numbers by six, so 10 times by six and four times by six.

So instead of trying to know our six times tables up to 14 times six, we're splitting it into more manageable questions and then we can put them back together again.

Now if you've got some online Dienes, you can see that we've got six lots of 10.

10 times six is six lots of 10 Dienes, and then four times six, six lots of four Dienes.

And we need to then work out what we've got here, so six lots of 10 Dienes, 60, and four times six is 24.

Remember that you can use your three times table if you're not feeling too confident with your sixes.

Four times three is 12 and then you can double 12 to get you to 24.

It's about making those connections between your maths knowledge.

Okay, we then need to add those together and we use column addition to make sure that we're adding them accurately.

We need to line up the ones and the tens and then start by adding our ones in case we need to regroup.

So zero add four is four, six add two is eight and there's our answer of 14 times six, 84.

Okay, here's how we're going to set it out today, and here's our success criteria.

I've already talked you through it, but it's a really clear step to get these accurate answers.

So the first thing, partition the two-digit number, second thing, multiply them both by six, and finally, don't forget to add them back together again.

So, partitioning, I've already done this for you on this question, I've partitioned 48 into 40 and eight, and then we just need to times each of them by six, easy.

So 40 times six, hmm, ah, I don't know my six times table up 40 times six, but I do know four times six.

Four times six is 24, can I use that to work out 40 times six? Well that's where that timesing by 10 comes in really handy.

I know that four times by six is 24, and so 40 times by six, or six times by 40, doesn't matter which order you put it in, is 240.

So, when we're doing the tens, we work out the answer that we know when we multiply by the ones or times by six, and then we make it 10 times bigger, and we're going to do that for every question in today's lesson.

Then we do eight times six, hmm, again you might be a bit stuck, but remember that you can use your threes to help you and double it to get your sixes.

So, eight times six is 48.

Don't forget the final part of your question though, I don't have an answer yet to 48 times six, I've got to add those two answers together, I've got to add 40 and eight to get to 48 times six.

So I'm going to use that column addition, line it up nicely and neatly so that I am adding in the correct column.

Starting with my ones, zero add eight is eight, four add four is eight, and then I bring my two down for my hundreds.

There's my accurate answer, 288.

Let's move on then.

Your go, I've done the first part of the success criteria for you.

This question is 52 times six.

I've split up 52 into 50 and two, you need to times them each by six, and then add them together with some column addition to get that answer.

Pause the video here for as long as you need, have a go at working out the answer to that one.

How did you get on? Let's have a look.

So 50 times six, which fact did you use to help you? Well hopefully you could see that five times six, changing 50 into five, five times six is 30, and then to get 50 rather than five, make your answer 10 times bigger.

So, 30 times by 10 is 300.

Six times by two, quite a nice easy one, is 12, and then column addition to add those together, 312.

Well done if you got all of those steps correct, really good.

Okay, another one here for you then, I'm not going to partition it for you this time or draw your grid, your turn to have a go at answering 33 times six.

Well done.

Now there's a few different steps in these questions, so well done if you're getting even just a few of them correct.

But if you are making a mistake, just listen really carefully and see what mistake you made and try your best not to make that next time.

So, the first thing you should've done is partition, so hopefully you drew a grid, split it down the middle, had six at the top, and 30 and three down the side.

If that's as far as you got, you've done the first part of your success criteria, so well done if you got something that looks like that on your paper.

The next thing in your success criteria says multiply each by six.

30 times by six, well I know that three times by six is 18, so 30 times by six, make that 10 times bigger, is 180, and then I've already done three times six is 18, and that's my answer there.

Well done if you got that far, but it's not the whole answer.

So, the final part of the question is just to add those two together.

So 180 add 18 is 198.

So, let's just do one word problem together and it's exactly same success criteria, it's just that you need to work out what the question is.

So, six children buy 47 sweets each, how many do they buy in total? So, I like to picture these children, there are six of them, maybe they're all a family or a big group of friends and they've all rushed into the shop and they're buying 47 sweets, that's quite a lot, maybe it's a birthday.

So, I like to picture it in my head, they're going to buy quite a lot of sweets, aren't they? So each child buys 47 sweets, so the question here is six and 47, 47 times six, or six times 47.

We then need to draw our grid out with six at the top and 47 partitioned at the side.

We then know that four times six is 24 so 40 times six must be 240, and seven times six is 42.

Adding those together with column addition gets us our final answer, 282, well done.

Okay, just a recap of what our success criteria is, if you follow this success criteria to your independent activity, you can't go wrong.

So partition, 35 becomes 30 and five, multiply each by six, 30 times by six, 180, and then five times by six is 30, and finally, add them together.

All of those followed properly and you'll get a right answer every time.

It's time for your main activity.

Part C is a little tricky, but just try some trial and error, try adding two different numbers together and see how you get on.

Okay, let's see how you did.

So, we've got these missing numbers here.

So hopefully you're able to follow the success criteria to answer these two-digit numbers multiplied by six, so 45 times by six is 270, 83 times by six, 498.

Something times by six is 300, well, I know that five times by six is 30 so it must be 50 times by six to give me 300, and then I can use that fact again to help me here, well 600 is double 300, so 50 doubled is 100.

Here it says that Jasmine was doing a calculation of 32 times six and she got the answer, 1812.

Now just looking at that answer, that looks too big for me, but if I work out the answer I could see actually it's 192.

I think the mistake Jasmine made here was she didn't add them together properly at the end, I think she ended up with 180 and 12, didn't quite add them together properly, so she made a little bit of a mistake on her column addition.

Here, hopefully you could see these answers, 150, 156, 162, and it's interesting to see how the hundreds, tens, and ones change in those columns there.

So in the first one we can see that we've just got hundreds and tens, then we've got ones, and by the last question, we've got an extra one in the tens as well.

With this word problem, Tim has bought 16 boxes of eggs each which contain six, so we've got 16 times six which we can split into 10 times six and six times six to give us the answer of 96.

The last question then, now what I needed to do to answer this question was write down all my sixes and all my eights and think about a combination of the two which would give me 100.

I finally got two and it did take me a little time, if I had 10 insects I'd have 60 legs and if I had five spiders, I'd have 40 legs and I could add those together for 100 legs.

If you got a different answer, as long as it adds up to 100, well done, you.

Fantastic work there, really lots of new learning and you did fantastically well.

Have a go at the knowledge quiz and see how much went in.

Well done, everybody, have a fantastic day, bye bye.