Video: KS1-M19 • Paper 1 • Question 25

73 − 19 = _.


Video Transcript

73 take away 19 equals what?

In this problem, we need to take away 19 from 73. 19 is one 10 and nine ones. We can take away one 10 from seven 10s. But how can we take away nine ones from three ones? We can break down or partition the number 73 to help us. We can take away 19 from 20 easily. So let’s make 20 one of our parts. We know 53 plus 20 equals 73. So Our two parts are 53 and 20.

First, we can take away 19 from the 20 part. 20 take away 19 equals one. Now, we need to just combine this with the rest of 73, which we said was 53. 53 plus what’s left after we took away which is one equals 54. And so, we know 73 take away 19 equals 54. Let’s model how we work the answer out using tens and ones cubes. We started with 73 which is seven tens and three ones. We said that the number 19 had one 10 and nine ones. And that this might be difficult to take away from a number that had three ones. So we split up 73 into a number that we could take away 19 from easily and whatever was left.

We decided that we could take 19 from 20 easily. And so, 73 was split into 20 and 53. First, we took away 19 from 20. 19 is one 10 and nine ones. And if we take away one 10 and nine ones from 20, we’re left with one one. So we’ve managed to take away 19 from 73.

Finally, we just needed to combine the two parts back together again to find the answer. And to do that, we added one to 53 which is 54. To help us see it more clearly in the model, let’s move this ones cube to join the other ones cubes, five 10s and four ones.

And so, 73 take away 19 equals 54.

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