Question Video: Writing an Additional Expression to Find the Missing Number Using Models | Nagwa Question Video: Writing an Additional Expression to Find the Missing Number Using Models | Nagwa

# Question Video: Writing an Additional Expression to Find the Missing Number Using Models Mathematics • First Year of Primary School

There are 6 apples, some are red and others are green. 2 of them are red. How many green apples are there?

02:22

### Video Transcript

There are six apples. Some are red and others are green. Two of them are red. How many green apples are there?

This word problem is all about a group. We’re told that this is a group of six apples. Some are red and others are green. But we don’t know to start with how many red and how many green apples there are. And that’s why in the first picture we can see six apples, but they haven’t been colored yet. At the moment, they’re all in shadow. And in our second sentence, we’re told a fact about our group of apples. We’re told that two of them are red. Because the apples are either red or green, we can also say that the rest are going to be green.

Now, the word problem asks us, how many green apples are there? You know, we can represent this problem using a part–whole model. There are six apples altogether, so we can say that the whole amount is six. Now, we can break up the number six into two parts: one representing red apples and one representing green apples. So let’s color-code our part–whole model.

We know that two of the apples are red. And we don’t know how many green apples there are. This is the part we need to find. To find our missing part, we could start with the whole amount, which is six, and take away the part that we know, which is two. Six apples take away two apples leaves us with how many apples?

Let’s model the problem using counters. We’ll start with six counters. We can take away two counters. And this leaves us with one, two, three, four counters. The number six can be broken apart into a group of two and a group of four because two and four go together to make six. If there are six apples — some are red; others are green — and we know that two of the apples are red, then we can say that the number of green apples is four.

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