Welcome to the video

on basic subtraction. Let’s do a little bit a review

of basic addition first. If I said 4 plus 3,

what did this mean? What did that equal? Well, there were a couple of

ways we could have viewed this. We could have said I

had 4 of something. Let’s say I had 4 circles

or I don’t know, I had 4 lemons for breakfast. So 1, 2, 3, 4 lemons

for breakfast. And let’s say, I had another

3 lemons for lunch. 1, 2, 3, and so you could

view 4 plus 3 as how many total lemons did I have? I’m adding 3 to 4. So how many total did I have? Well, it’s 1, 2, 3, 4, 5, 6, 7. So I had a total of 7 lemons. Another way we could have

viewed that is we could have drawn our number line. And I’ll draw it in yellow

because– now that’s not wide enough. I’ll draw it in yellow because

we’re talking about lemons. So let’s say that’s

our number line. And if I start at the number–

let me draw all of the numbers. 0, 1, 2, 3, 4, 5, 6, 7. So you could think about

this as saying, well, we’re on the number line. We start at the number 4. That’s this number 4. And we’re adding 3 to it. So we’ll increase, along

the number line by 3. So we’ll go 1, 2, 3

and you end up at 7. So you could say if I have 4

and I get 3 more, I get 7. Or if I increase 4

by 3 I also get 7. So what’s subtraction now? Because that’s what

this video is about. I shouldn’t waste all of our

time talking about addition. So let’s take the

example of 4 minus 3. What is that equal to? Let me switch colors just to

keep things interesting. So what is 4 minus 3 equal to? Subtraction or minus is

the opposite of addition. So in addition you’re doing

something more, you’re adding. I don’t want to use the word

adding to define addition, but that’s what you’re doing. I had 4 lemons and

then I had 3 more. In subtraction

you’re taking away. So this example, if I started

with 4 lemons, let’s say I had 4 lemons on a plate. If I’m subtracting 3, if I’m

saying minus 3, instead of adding these 3 and getting 7,

I’m going to take 3 away. So maybe I’m eating them

or maybe I’m giving them to you in exchange for

watching these videos. So to take away 3 from this 4,

let’s say this one goes away, this one goes away, and

this one goes away. How many lemons

would we have left? Well, this is the only one

that I haven’t crossed out. So we would have 1 lemon left. And this would be the

lemon that’s left. Didn’t have to be that

one, I could have crossed out any of the 3. Another way to view that,

let’s draw the same lemon colored number line. Let’s say that this is the

number line right here. And I’ll draw all

the same numbers. So that’s 0, 1, 2,

3, 4, 5, 6, 7. Of course, the number

line keeps going. There’s no largest number. And you can imagine, any number

that you can think of, I can think of one higher than that. So there is no largest number. So that’s why we draw

that arrow there. I could never draw the

entire number line. But anyway, back

to subtraction. So we’re starting at

4 lemons, right? When we added 3– plus 3– we

went to the right 4 spaces on the number line. And that’s because the

right is increasing value. So we went from 4 to 5. That was one more. 5 to 6 was two more,

and 7 was 3 more. Now we’re taking away from 4. So what do we do? What would you think we do? Well, since we’re taking away

we’re going to decrease the total number of lemons we have. So we take away

one, we get to 3. Take away two, get to 2. Take away three, we took

away three, right? So we’ll go back 1, 2, 3

along the number line and we’ll end up at 1. And that’s this 1 right here. So just to review, addition is

you’re doing more or something. Subtraction is you

are taking away. If you think about it on the

number line, addition is increasing along the number

line by that amount. So in this case we increased

along the number line by 3. And so we went from 4 to 7. In the subtraction case

we decrease back on the number line. So we decrease by the amount

that you’re subtracting. So in this case we

decreased by 3. We went back 1, 2,

3 and we had 1. And the other way to view it,

if I have 4 of something. If I give 3 away or if I ate

3 of them or I don’t know what I did to 3 of them. If I lost 3 of them I

would have 1 left. Now let me show you some

interesting things about subtraction. So we know that 4 minus

3 is equal to 1. Let me show you something

else that’s interesting. What is 4 minus 1? Well, we could use

either example. Let’s do the lemon example. Let’s do apples now; I’m

bored of the lemons. Let’s say I 1, 2, 3, 4. I have a new pen, sometimes

it doesn’t draw right. Let’s say I had 4 apples. This is the example

we’re dealing with. And I were to eat one of them. So one of them were to go away. How many apples

would I have left? Well, 3– 1, 2, 3. So 4 minus 1 is equal to 3. And if we did it on the number

line, if we started at 4 and we subtracted 1– we took 1 away. So we’re going to

become one smaller. We go back one, we get 3. Either way works. But isn’t this interesting? 4 minus 3 is equal to 1 and

4 minus 1 is equal to 3. You might say, well, did I pick

the numbers just so it worked? Well, it turns out that

it’s always true. Well, I don’t want to get too

technical, but we’re already touching on something that

you’ll learn later, maybe in algebra one day. But actually I don’t want to

go into all that right now. So where does this come from? Well, this is also based on

the fact that 3 plus 1– I didn’t want to confuse you. So I apologize if I did. But I’ll show you another

interesting thing. What is 3 plus 1? 3 plus 1 is equal to what? Well, that’s easy. You know that from

basic addition. You can start on the number

line at 3 and add 1 do it. And where do you end up? You end up at 4. 3 plus 1 is equal to 4. Or you could have started at 1

on the number line and added 3. 1, 2, 3 and you would

have also ended up at 4. So we also know that you could

have switch this either way. Both of those are equal 4. What do you see here? Well, there’s a bunch of things

I’ve written here and they all kind of relate to each other. 1 plus 3 is equal to 4. 3 plus 1 is equal to 4. 4 minus 1 is 3. Essentially, 4 minus 1 and

getting 3 is the exact same– you’re saying the same thing

as 3 plus 1 is equal to 4. This statement says if

I add 1 to 3 I get 4. This is saying if I take

away 1 from 4 I get 3. So if I start at 4,

move back, I get 3. This is saying if I start at

3, and I move up 1, I get 4. Hopefully that gives you a

little bit of intuition about what subtraction is. In the next video I’ll just do

as many basic subtraction problems I can do

in 10 minutes. And then you’ll be ready

to do the exercises. See you soon.

^_^

ur BORED of the lemons? Lol wow

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@LordAlda I fapped to this comment.

@Shadyhunter04 Im 17 And I watch this videom because I need some help with math! Got a problem?

i don,t like lemons

@lizardgizzard108 no i do to!!

Excellent videos. If there's one positive piece of criticism I can give you. I know what part of the board you are talking about but the average child would have a hard time following it.

Solution: make the pen tip much more visible.

Thanks.

Ahhh I still don't get it!

I don't eather

Who has four lemons for breakfast?!

your way is fantastic. thank you very much

I still don't get it.

>lemons for breakfast and lunch

If I ever have kids, this is what they are going to watch.

Gonna use some of your vids homeschooling next year!!

hey im wearing a bra whats up niggas

This shit is so hard to understand!!

Sorry, cab someone please explain to me the end from the 3 plus 1 part.

Sorry, how does information at the end go into Algebra?

Can*

Please, ask simple question. What didn't you understand exactly?

Do you want us to explain what is algebra?

what is your question exactly?

He says we'll see that in A;egabra and I am wondering, ho wdo we see it in Algebra?

1 number

I love that Video. Also

Thanks for the video! For another fun way to learn basic math, check out the exciting new card game, Combination!

The lemons were a bad idea, I would never eat any plain

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Crainer fans u shouldn't be his fans anymore

#perfectexplanation

Who the heck eats lemons for their meals

my goodness these are like the first Khan Akedemy videos

zzzzzzzzzz,huh?

oh i do Khan Academy,thanks!

crickets in background

Three Rivers school

Write the degree of the following polynomial. ab2cd – 3a2bcd3 +2ac4.

Im software engineer and im watching this video.. wanted to clear some doubts.. :-D.. nicely explain..

Hi a don’t like math my dad made me watch this

you have a cool channel