Video: Dividing Two-Digit Numbers by One-Digit Numbers Using Part–Whole Models

Use the part–whole model to find 84 ÷ 3.

02:31

Video Transcript

Use the following part–whole model to find 84 divided by three.

Often, we can use times tables facts we already know to help us with a division. But do you know a times tables fact that’s going to help you find 84 divided by three? It’s quite a large two-digit number we need to divide, isn’t it? And that’s why in this question we’re shown how to split it up into smaller parts to help us. The whole amount in the part–whole model that we’re given is 84; it’s the number we’re dividing. And we can see it’s been split into two parts, 60 and 24. Now, often when we break apart two-digit numbers to make them easier to work with, we split them up into their 10s and ones. But with this calculation, it would have meant splitting up the number into eight 10s or 80 and four ones.

But if our part–whole model had shown 80 and four, we’d have found it really difficult to divide by three. Neither of these parts are multiples of three. And that’s why we’ve been given this particular part–whole model to help us. Both 60 and 24 are multiples of three. And they’re also multiples of three that we already know facts for. So we can divide each part by three to help us find the overall answer. First of all, how many threes are in 60? Well, this is still quite a large number, but we know a fact that can help us. We know that 10 threes are in 30. 30 divided by three equals 10. And so, if we double 30 to get 60, we double the number of threes that we have.

60 divided by three equals 20. Now we need to divide the second part by three. How many threes are there in 24? Three, six, nine, 12, 15, 18, 21, 24. There are eight threes in 24. We found out there are 20 threes in 60 and eight threes in 24. And 20 plus eight equals 28. We’ve used the part–whole model to find that 84 divided by three equals 28.

Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.