Video: Subtracting One-Digit Numbers from Two-Digit Numbers

Isabella has 12 coins. After she puts some in a bag, there are 7 left. So, there are 12 − 7 coins in the bag. How many coins are there in the bag?

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Video Transcript

Isabella has 12 coins. After she puts some in a bag, there are seven left. So, there are 12 take away seven coins in the bag. How many coins are there in the bag?

We could use 10 frames to help us answer the question. We can make 12 using a full 10 frame with 10 counters and two more. We put 12 counters in our 10 frames because Isabella has 12 coins. We know that Isabella put some of her coins in a bag, and then there were seven left. The question is asking us to work out how many coins there are in the bag. Or, how many did Isabella take away?

Let’s start with our 12 counters or 12 coins and take away until we reach seven. If we take away one, we’ll have 11 left. If we take away two, we will have 10 left. Now, we’ve got an empty 10 frame. We just have 10. So, we’ve taken away two. Let’s take away one more. That means we’ve taken away three. And now, we have nine counters left. If we take away another counter, we will have eight counters left. And, if we take away one more, we will have seven. We had 12 counters and we took away five. 12 take away five equals seven. There are five coins in the bag. Five plus seven equals 12. And 12 take away five equals seven. There are five coins in the bag.

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