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## 2nd grade

### Unit 2: Lesson 3

Regroup whole numbers# Regrouping whole numbers: 675

CCSS.Math: , , ,

Sal regroups 675 into various addition problems. Created by Sal Khan.

## Want to join the conversation?

- is there anyone on here like a teacher or someone who could teach me or help me understand the whole algebra thing and such? I only have my GED math test holding me back, I have ADHD and it has just really been a burden trying to get through my math alone. (I'm sure you know ADHD and math don't mix, LOL) I see comments and such but they are like...from 3 years ago, are there people still active on here enough so as I could get some help? if not.....well...I'm used to being alone. if anyone read this, thank you.(89 votes)
- I have an anxiety disorder and I've tutored people who have ADHD before, so I understand your struggle. If you have an emotional or stress-related block when it comes to math, you can overcome it - I promise.

One of the best things to do is join a community of learners (like this one on Khan Academy), who are trying to learn the same thing and feel the support of other people who are there to help you.

The next thing is to try to set a series of smaller goals on the way to the big one, the GED! Khan Academy has already broken up the lessons really well and provided the positive feedback (like points and badges) that help you feel good about how much you already know and celebrate each new thing you learn. Each grade level and subject matter of math you master brings you closer to your big goal of getting your GED.

I have found that the best way to verify your expertise and pat yourself on the back for learning a new set of skills is to try teaching or explaining it to someone else who might be confused. Try it - you'll feel great about what you know and about being "smart" enough to help someone else. You can do this while still progressing forward on the next lessons, videos and master challenge tests waiting for you.

Then, when you feel bogged down and confused and want to shut down again - just switch gears and become someone else's teacher for a while. It's true - "a change is as good as a rest."

Finally, do what Kim Seidel suggested and ask questions of us in the community about things that still confuse you.

Don't give up - you're worth the effort. And you can do it!(62 votes)

- I'm not understanding the concept of regrouping whole numbers in this video lecture. Are subtracting from these whole numbers to simplify the equation? I'm lost on this information. Crossing the numbers out and throwing lower numbers don't tell me anything. I throw my hands up in the air.(21 votes)
- HOW DO YOU GUY UNDERSTAND BUT NOT ME YOU GUY UNDERSTAND THE VIDEO BETTER THAN ME?😮💨😔😞 THANKS AND THE BUT IT DOESN'T HELP ME UNDERSTAND.😟😞 I HATE MYSELF🤬😓😮💨 you guys know better than me.😞 You guys are the best at regrouping whole numbers.😢 I love you guys so much good luck for who want to be same one in there life's.🌟🥰🎁😮💨(10 votes)
- I feel so sad, I love you to! :)(2 votes)

- Hi,

I need help understanding. I have watched the video a few times but still don’t understand what Sal did(6 votes)- Let's think about different ways that we can represent the number 675. So the most obvious way is to just look at the different place values. So the 6 is in the hundreds place. It literally represents 600. So that's 600. I'm going to do that in the red color-- 600. The 7 is in the tens place. It represents 7 tens, or 70. And then the 5 in the ones place. It represents 5. So let me copy and paste this and then think about how we can regroup the value in the different places to represent this in different ways. So let me copy and let me paste it, and maybe I'll do it three times. So let me do it once, and let me do it one more time. So one thing that we could do is we could regroup from one place to the next. So, for example, we could take if we wanted to-- we could take 1 from the hundreds place. Taking 1 from the hundreds place will make this a 5. That's essentially taking 100 away. So this is really making this a 500. And we could give that 100 to-- well, we could actually give it to either place, but let's give it to the tens place. So we're going to give 100 to the tens place. Now, if you give 100 to the tens place and you already had 70 there, what's it going to be equal to? Well, it's going to be equal to 170. Well, how would we represent that is tens? Well, 170 is 17 tens. So we could just say that 7 becomes 17. Now, we could keep doing that. We could regroup some of this value in the tens place to the ones place. So, for example, we could give 10 from the tens place and give it to the ones place. Let's do that. So let's take 10 away from here. So that becomes 160. This becomes 16. And let's give that 10 to the ones place. Well, what does the ones place now become? Well, 10 plus 5 is 15. So this 5 is now a 15. Let's do another scenario. Let's do something nutty. Let's take 200 from the hundreds place. So this is going to now 4, and this is going to become 400. That's what this 4 now represents. And let's give 100 to the tens place. And let's give another 100 to the ones place. So in other words, I'm just regrouping that 200. Those 200's, I've taken from the hundreds place, and I'm going to give it to these other places. So now the tens place is going to be 170. We're going to have 170 here, which is 17 tens. So you could say that the tens place is now 17. And now the ones place, well, I had 5, and now I'm going to add 100 to it. So it's going to be 105. And 105 ones is literally 105. And notice, this is 400 plus 17 tens, which is 170 plus 105. You add these together, you're still going to get 675. Let's do that again. So let's take, I don't know. Let's take all of the hundreds away. Let's take all of the hundreds away. So that goes zero. That goes zero. And let's give 400 to the tens place. So let's give 400 to the tens place. Well, that'll make that 470. Let me do that in that green color. That will make that 470, which is the same thing as 47 tens. And then I still have 200 to give to the ones place. So let me do that. So I still have 200 to give to the ones place. And so that's going to go from 5 to 205. Once again, all I've done is I've regrouped the value in the number 675. Any of these still represent 675. You can add these numbers on the right. They all add up to 675. Will this help vincent?(5 votes)

- How can pepole understand this and im about to flush my computer down the toliet im going to sue you when i get olderrrrrrrrrrrr(3 votes)
- No one is going to take you seriously if you threaten to sue someone or flush your computer down the toilet. Instead, you should explain your concern in a respectful and constructive way so that people can understand you and help you. Hope that helps! - Alex(2 votes)

- wait i dont understand lke wth regrouping frick man im bad at regrouping well others cant understand im so sorry for that is about learning but looks like not i wish this make more understanding bro

thats all(2 votes)- In math, regrouping can be defined as the process of making groups of tens when carrying out operations like addition and subtraction with two-digit numbers or larger. To regroup means to rearrange groups in place value to carry out an operation. We use regrouping in subtraction, when digits in the minuend are smaller than the digits in the same place in the subtrahend. To explain the concept of regrouping in addition and subtraction better, begin by introducing the concept using tens and ones blocks to show how to regroup 10 ones as 1 ten. If you still don't get it, here's a fun rhyme to help!

*Let's sing!**It’s time to trade with ten or more.*

Give some or borrow ten from next door.

Then, add or subtract, and you will score!

Hope that helps! - Alex(4 votes)

- Can someone explain this differently?(3 votes)

## Video transcript

Let's think about
different ways that we can represent the number 675. So the most obvious
way is to just look at the different place values. So the 6 is in the
hundreds place. It literally represents 600. So that's 600. I'm going to do that
in the red color-- 600. The 7 is in the tens place. It represents 7 tens, or 70. And then the 5 in
the ones place. It represents 5. So let me copy and paste
this and then think about how we can regroup the
value in the different places to represent this
in different ways. So let me copy and
let me paste it, and maybe I'll do
it three times. So let me do it once, and
let me do it one more time. So one thing that we could do is
we could regroup from one place to the next. So, for example,
we could take if we wanted to-- we could take
1 from the hundreds place. Taking 1 from the hundreds
place will make this a 5. That's essentially
taking 100 away. So this is really
making this a 500. And we could give
that 100 to-- well, we could actually give
it to either place, but let's give it
to the tens place. So we're going to give
100 to the tens place. Now, if you give 100
to the tens place and you already had 70 there,
what's it going to be equal to? Well, it's going
to be equal to 170. Well, how would we
represent that is tens? Well, 170 is 17 tens. So we could just say
that 7 becomes 17. Now, we could keep doing that. We could regroup some of
this value in the tens place to the ones place. So, for example, we could
give 10 from the tens place and give it to the ones place. Let's do that. So let's take 10 away from here. So that becomes 160. This becomes 16. And let's give that
10 to the ones place. Well, what does the
ones place now become? Well, 10 plus 5 is 15. So this 5 is now a 15. Let's do another scenario. Let's do something nutty. Let's take 200 from
the hundreds place. So this is going to now 4, and
this is going to become 400. That's what this
4 now represents. And let's give 100
to the tens place. And let's give another
100 to the ones place. So in other words, I'm
just regrouping that 200. Those 200's, I've taken
from the hundreds place, and I'm going to give it
to these other places. So now the tens place
is going to be 170. We're going to have 170
here, which is 17 tens. So you could say that
the tens place is now 17. And now the ones
place, well, I had 5, and now I'm going
to add 100 to it. So it's going to be 105. And 105 ones is literally 105. And notice, this is 400 plus
17 tens, which is 170 plus 105. You add these together,
you're still going to get 675. Let's do that again. So let's take, I don't know. Let's take all of
the hundreds away. Let's take all of
the hundreds away. So that goes zero. That goes zero. And let's give 400
to the tens place. So let's give 400
to the tens place. Well, that'll make that 470. Let me do that in
that green color. That will make that 470, which
is the same thing as 47 tens. And then I still have 200
to give to the ones place. So let me do that. So I still have 200 to
give to the ones place. And so that's going
to go from 5 to 205. Once again, all
I've done is I've regrouped the value
in the number 675. Any of these still
represent 675. You can add these
numbers on the right. They all add up to 675.