Main content

## 5th grade (2018 edition)

### Unit 4: Lesson 11

Regrouping decimal numbers# Regrouping whole numbers: 76,830

Sal regroups 76,830 by its place values. Created by Sal Khan.

## Want to join the conversation?

- On this video it is saying 76,830. I thought it was suppose to say 7 ten thousands, 6 thousands, 8 hundreds, and 3 tens. But why is it saying 6 ten thousands then 7?(3 votes)
- It's not saying "6 ten thousands and then 7",

it's saying "6 ten thousands plus [blank] thousands..."

7 ten thousands = 6 ten thousands + 10 thousands,

so 76,830 = 6 ten thousands + 16 thousands + 8 hundreds + 3 tens.(8 votes)

- What on earth is the point of re-grouping anyway? I can't think of a single use for it. I don't even use it for subtraction.(3 votes)
- Sal is demonstrating different ways to regroup numbers in order to make addition/subtraction easier, when working with more awkward and difficult numbers.

Number he is using is quite easy. It breaks down into nice, even 'chunks': 600 + 75 + 5 , which are easy to add/subtract.

But say you had more awkward numbers, something like this:

437 + 789

You could break them down into 'chunks' which are easier for you to manipulate:

437 = 400 + 30 + 7

789 = 700 + 80 + 9

or whatever 'chunks' are easier for you to work with.

And then just combine all the 'chunks' together:

700 + 400 + 80 + 30 + 9 + 7 -> 1100 + 110 + 16

Then

1210 + 16 = 1226 or 1100 + 126 = 1226

Or in any other way you want to combine you 'chunks'

Same for subtraction

With practice you'll be able to add/subtract large numbers in your head, without a calculator.(3 votes)

- Is regrouping of whole numbers important(4 votes)
- how many times do we regorup(4 votes)
- ask your teacher how to start a program so my teacher knows.(4 votes)
- how much is 5000+10000=15000(2 votes)
- how does a video help others who already know this?(2 votes)
- It can be set as a refresher course for them.(0 votes)

- how do you feger out the missing number(1 vote)
- how do you feger out the eqution(1 vote)
- What is the purpose behind this regrouping? I understand how to do it but not understanding the why.(1 vote)
- It helps you understand how place values relate to each other. We also use regrouping when dealing with money. There are a lot of different ways that you can pay someone $63

3 - twenties and 3 ones

2 - twenties, 2 tens and 3 ones

1 twenty, 4 tens, 2 fives and 3 ones

etc.(1 vote)

## Video transcript

Fill in the blanks to
complete the equation. So they have 76,830 is
equal to 6 ten thousands plus blank thousands plus
8 hundreds plus 3 tens. So let's just
think about 76,830. So if we write 76,830-- I'm
going to try to color-code it. We could write this out as
being the same thing as 70,000 plus 6,000-- the 7 is in
the ten thousands place. So it's 7 ten thousands,
which is 70,000, plus-- the 6 is in the thousands place--
so it's 6,000, or 6 thousands, one could say, plus 800. Or you could say 8 hundreds. 800 plus 3 tens, or 30. And then there's 0
ones, so we could just write that out as 0 if we like. Now, what we have
on the right here is almost what they have
on the right over here. Notice the 0. They didn't write that. So we can ignore that. The 0 really doesn't
affect the value. We have 3 tens. We have 3 tens. Let me do this in a
color you can see. You have 8 hundreds. You have 800. But then that's where
it starts to break down. They have blank thousands. Here we have 6 thousands. So we're going to have to
think about this a little bit. And then they have 6 ten
thousands, which is 60,000. Here we have 70 thousands. So we've got to work
through these two places right over here. So they have 6 ten
thousands, which is the same thing as 60,000. We have 70,000. So they essentially
took 10,000 from here and regrouped it someplace. And since these two
places are the same, they must have regrouped it
into the thousands place. So let's try to do that. So let's get rid of
10,000 out of the 70,000. It becomes 60,000. So this becomes a 6. And then we're regrouping
that into the thousands place. So we're going to add 10,000
to the thousands place. Now what's the thousands
place going to be then? Well, it's 10,000 plus 6,000. It's going to
become 16 thousands. This right over here is
going to become a 16. So now what we wrote
here looks just like what they wrote up here. This is 6 ten thousands
plus 16 thousands plus 8 hundreds plus 3 tens. And we're done.