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## Addition and subtraction greater than 1000

Current time:0:00Total duration:4:28

# Multi-digit subtraction with regrouping: 7329-6278

## Video transcript

We have 7,329 minus 6,278. So let's go place by place
and see if we can subtract. 6,278 is clearly
less than 7,329, so we should be able to do this. So first, we go
to the ones place. We're subtracting an 8 from a 9. That seems pretty
straightforward. That's just going to be a
1, a 1 in the ones place. It literally just represents 1. Then we go to the tens place. And we're trying to
subtract a 7 from a 2. And this is really
representing 70. And this is really
representing 20. Well, now we're hitting a
bit of a stumbling block. So we're going to have
to regroup or borrow. And to understand
what we're doing, let's rewrite both
of these numbers. So 7,329-- 7 we can rewrite
as being equal to 7,000. Plus 300-- so this 3
in the hundreds place is representing 300. The 7 in the thousands
place is 7,000. 3 in the hundreds place is 300. The 2 in the tens place,
that's two 10's, or 20. And then the 9 in the ones
place is just going to be 9. So this is another way
of representing 7,329. And then down here, we have
the 6 in the thousands place. Well, that's going to be 6,000. And we're subtracting,
so minus 6,000. And then here, we have a
2 in the hundreds place. And once again, we're going to
be subtracting all of these. So we're going to
be subtracting 200. And then here in the tens
place, we have our 7. And we're subtracting it. So seven 10's, that's 70. And then we are
subtracting that 8. And what we've already
done is said, hey, look. Subtracting 8 from 9? That's just going to be 1. But then we got over
here, and we said, hey, how are we going
to subtract 70 from 20? And the key here is to regroup
some of the value up here and give it to
the tens place, so that we can subtract 70 from it. And the most natural place to
go is one place value above. So we could take
100 from the 300. So then it will become 200. We're going to give 100--
we're going to give that 100 to the tens place. So it is going to become 120. Notice, 200 plus 120 is 320. 300 plus 20 is 320. We have not changed the
value of the number. We've just changed what place
we're representing it in. If we wanted to do it
here, we could say-- and when you think of it this
way, this is really regrouping, and this is really
what's happening. But if you want to think of
it in a borrowing framework, you could say, hey,
let's take 1 from the 3. Although it's a 300, so
you're really taking 100. That becomes a 2. And you give that 1
to the tens place. And so that becomes a 12. Now, what was really
happening is you took 100. You gave it to the 20. It became 120. But now you can subtract. Here, you'd say, well,
what's 120 minus 70? Well, 120 minus 70
is going to be 50. Over here you could say,
well, what's 12 minus 7? Well, that's 5. But it's still representing
the same thing. 12 10's is 120. Seven 10's is 70. And they give you five 10's,
which is the same thing as 50. This 5 represents that 50. And then we can go
to the other places. You say 2 minus 2. Well, that's zero 100's. And then 7,000 minus
6,000 is 1,000. And once again, right over here,
200 minus 200 is zero 100's. And then 7,000 minus
6,000 is 1,000. So this is going to be
1,000 plus 0 plus 50 plus 1, which is the
exact same thing as 1,051. The important thing
is to visualize-- you don't have to write
this out every time. But to make sure you
visualize in your head that this 3 is representing
300, that this 2 represents 20, that when you're taking
100 from the 300, then you would represent that
as a 2 in the hundreds place. And then when you give
100 to the tens place, it's essentially that the
two 10's will become 12 10's. Because you're giving
it 10 more 10's. You're giving it 100. So hopefully, that
makes some sense.