Question Video: Completing Subtraction Sentences to Represent the Same Part–Whole Model Mathematics • 1st Grade

Find the missing numbers in the subtraction sentences matching the part–whole model.

03:11

Video Transcript

Find the missing numbers in the subtraction sentences matching the given part–whole model. Five subtract four equals what. What subtract one equals four. One equals what subtract four. And four equals five subtract what.

In this question, we’re given four subtraction sentences and we need to find the missing numbers in them. To help us, we’re given a part–whole model. Let’s take a moment to look at it. The top number here is the whole amount, five. Let’s draw five counters to represent this whole amount. There we go. At the bottom of our part–whole model, we can see two parts that we can split the whole amount into, and they are four and one. Let’s color our counters to show that four and one go together to make five. There we are. Four and one make five.

Now let’s try to use this part–whole model and our counters to work out our missing numbers. Five subtract four equals what? Well, if we start with five counters and we take away four counters, we’re going to be left with the part that goes together with four to make five. Watch what happens when we point to the numbers on our part–whole model. Five take away four leaves us with one.

In the next subtraction, it’s the first number that’s missing. This is the number that we’re taking away from. What take away one leaves us with four? Well, as we’ve said already, we know that one and four go together to make five. And so, if we start off with five and then subtract one, we’ll be left with four. Can you see how our subtractions so far are all to do with this part–whole model? They’re part of a family of subtractions. They’re all linked.

Do you think the next two are going to be part of the same family? One equals what take away four? This is interesting because we start with the answer in this sentence. One is what we’re left with if we start with something and take away four. Can you see this is exactly the same as the subtraction above it? If we know that five take away four leaves us with one, then we know one is what we get if we start with five and take away four. The missing number in this calculation is five.

And for our final subtraction, the family four is what we get when we start with five and take away what. Well, we know the missing part here is one. Four equals five take away one. In this question, we used a part–whole model to help us find a whole family of subtractions that are all linked. They all contain the same numbers. Five take away four equals one. Five take away one equals four. One equals five take away four. And four equals five take away one. Our missing numbers were one, five, five, and one.

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