Rob LangmanChief Commercial Officer at Third Space Learning

Teach Formal Written Subtraction (With Exchanging)

Name: Teach Formal Written Subtraction (With Exchanging)
Uploaded: 2024-04-04T07:23:12+00:00
Duration: 1 min 49 s
Channel: Rob Langman
Description: A short instructional video in which Brooke demonstrates formal written subtraction using exchanging (previously called borrowing). Using the example 23…

4 Apr 2024 · 2 min

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A short instructional video in which Brooke demonstrates formal written subtraction using exchanging (previously called borrowing). Using the example 23 − 16, she explains place value, exchanges one ten for ten ones to allow 3 − 6, performs the subtraction to get 7, and verifies the answer against the story problem. The video emphasizes the preferred terminology "exchanging" because nothing is borrowed and returned.

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Hi, I'm Brooke, and in this video we're going to be doing formal subtraction with exchanging. So this question requires us to exchange a 10 for 10 ones. Now, this used to be called borrowing. However, that's not accurate because we're not borrowing a 10 and giving it back. We're exchanging one 10 for 10 ones. So David has 23 grapes and he eats 16. How many grapes does he have left? So first of all, I'm going to start with the number of grapes he has to begin with, which is 23. And you can see that I've represented this here using my place value chart. I'm then going to subtract 16. First of all, I'm going to subtract the ones, so three take away six. However, I can't do that because I don't have enough ones. So this is where we introduce exchanging. Going to exchange one of my 10 for 10 ones. So I'm going to represent this with 10 ones in the ones column, like so I now have 13 ones. And we can show this on the formal written method by exchanging 110 for 10 ones. So we can see we've got 13 ones here and I can take away six, which is seven. I've got seven ones left. I can then subtract the tens. So I've got 110 and I'm taking away 1 10, which leaves me with 0 tens. Now I've got the answer, I can refer back to the problem. So David has 23 grapes, he eats 16, which gives him seven left, and that's how you subtract using the formal methods with exchanging.