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## 1st grade

### Course: 1st grade > Unit 2

Lesson 3: Subtraction within 20# Subtracting 14 - 6

Sal subtracts 14 - 6 by first thinking about subtracting 2 and 4. Created by Sal Khan.

## Want to join the conversation?

- Is 18-16 2 or is it 3? I think it is 2, but I am not shure.(9 votes)
- It is 2 because 1-1=0 and 8-6=2 I hope this helps(4 votes)

- What is a mathematical expression(5 votes)
- A mathematical expression is a sequence of numbers and operations. However, it does not include an equal sign. ex. 6+4-5x75 is a mathematical expression. 7-4=3 is not a mathematical expression.(8 votes)

- hi i gust wont to ask wunt is 14 mienes 6(6 votes)
- 14 is 1 ten plus 4 ones and 6 is 0 tens plus 6 ones.

We subtract the 6 from the 10 and we get 4.

If we add that 4 with the other 4 we get 8.

14-6=8(5 votes)

- Hi there,

Could you please tell which video explains how to do 9-[]=5 and []-4=5.

Any help on this is much appreciated.(7 votes)- Hello,

In these type of problems all you have to do is do the opposite of what it's asking. But, you would, in this case, still subtract since you are trying to find the number you subtract by and not the number you subtract from. So, 9-5=4 the missing value is 4.

For the second problem you add since you are trying to find the number you subtract from. So, 4+5=9 the missing value is 9.

Hope this helps!(2 votes)

- I am struggling to find a video on Subtracting within 20 with regrouping. I dont want to use blocks, I don't want to use visualizations. I want to know how to know how to write subtract 9 from 16 with regrouping.(3 votes)
- Try this,

We have the original number, but we can put it in**expanded form***.

So, 16 = 10 + 6, and we can use this.

We know that 10 - 9 = 1, and then we can add the remaining 6 to get**7**.**Expanded form is just taking the values of each number and adding them to create a number. For example, 17 = 10 + 7**, like

You can also use this for bigger numbers

1,234 = 1,000 + 200 + 30 + 4(7 votes)

- 14_2=12 and 14- 4=10 14_6=8(3 votes)
- Remember what Leo says, "The price is always right if come on down"(2 votes)

- how is 1 plus 51 = what?(3 votes)
- For example, think you have 51 things in a group and I want to add 1 more thing in that group (51 + 1), I would get
**52**things in the group as an answer.(2 votes)

- IF possibly, 10+4-4=10,

then why not,10*4-4=10??(2 votes)- Multiplying (that *) is really nothing else than adding the same number several times. In the case of "10*4", this really means the same as "10 + 10 + 10 + 10". So, if we rewrite your expression, we get:

10*4-4 = 10+10+10+10-4

And then you just go from left to right, remembering each answer:

10+10+10+10-4 = 20+10+10+4-4 = 30+10-4 = 40-4 = 36.

In the original expression we also simply go from left to right:

10+4-4 = 14-4 = 10.

So you see, there is nothing special about that "4-4".(4 votes)

- This is how you do it. 14 is equivalent to 7 and you subtract that. BUT THEN 7 IS ONE MORE, SO YOU ADD 3!! That's how you do iT1!(3 votes)
- Do any of you know what is the sum? 5000 5000 5000

+*___*(1 vote)- If you mean 5,000 + 5,000 + 5,000, then yes. :)

it is= 15,000(5 votes)

## Video transcript

Voiceover:Let's see if we can compute what 14 - 2 is, and then
figure out what 14 - 4 is, and then figure out what 14 - 6 is. And I encourage you to pause this video and try to figure these out
before I work through them. Voiceover:So I'm assuming you've given it a try, now let's think about it. The number 14 just by how it's written, we know that it's going
to be 1 group of ten. That's what this 1 tells
us plus another 4 ones. So let's verify that we
have 14 objects down here. This is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. So we definitely have a group of ten. We have 1 group of ten here,
so that's my group of ten. So let me box that off,
so I have my group of ten. And then how many ones do I have? I have 1, 2, 3, 4, I have four ones. So this is indeed, 14. This one that we have right over here, this represents this
ten, it's 1 group of ten. This is 1 group of ten,
let me write that down. Group of ten. And then we have 4 ones,
4, I guess we could say, 4 ones like that, so that is indeed 14. Now let's look at each of
these, what is 14-2 going to be? Well we could take away
2, so take away 1... take away 2, and how
many are we left with? Well we still have our one group of ten, so it's going to be 1,
followed by how many ones do we have left over, well we have 2 ones. We have 2 ones left over. 1, 2, so we are going to be left with 12. Now what about 14 - 4?
So let me clear this out. Actually let me do it like this. So if I clear that, so
what is 14 - 4 going to be? So now I'm going take away 1, 2, 3, and 4. I have essentially taken away all 4 ones. So what am I left with? Well I still have my 1 group of ten, I still have my 1 group of ten
and I have 0 ones left over. No ones anymore, so now I have 0 ones. And so 14 - 4 is 10, and that makes sense. 14 is 10 + 4 and now we're subtracting 4, to get 10, let me write this down. This is the same thing, 14 is 10 + 4. Voiceover:10 + 4, this is 14 and then we're going to subtract 4, Then we're subtracting 4,
so if you have 10 + 4 - 4. Well the 4 - 4 is going
to be 0, you're going to be left with 10 + 0 or just 10. We can do the same thing up here. This is equal to 14 is 10 +
4 and then we subtracted 2. And then we subtracted 2. So what you're going to be
left with 10 + what's 4 - 2? It's 2, so that's what
we got right over here. Let me make this very
clear, this simplifies to 2. This 2 right over here. This simplifies to 0,
this 0 right over here. Now let's do the last one, what is 14 - 6? Well we're going to take away 1, 2, 3, 4, then 5, and 6, so now we've
broken into our group of ten. So this is going to be a one-digit number. And we are left with
1, 2, 3, 4, 5, 6, 7, 8. So this is going to be equal
to 8 and we're all done.