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## 1st grade

### Course: 1st grade > Unit 2

Lesson 2: Addition within 20# Adding 5 + 3 + 6

Sal adds 5 + 3 + 6 two ways.

## Want to join the conversation?

- Can 5+3+6 become 5-3-6 ?(17 votes)
- Impossible cuz 5 - 3 - 6 = Negative 4(16 votes)

- But what if I get stuck on the same number and I keep on getting it wrong what should I do😞(6 votes)
- What I would recommend doing is splitting up the problem into smaller step. Let's take 3 + 9 + 2 + 4 + 3 + 4 + 5. It kinda looks scary right? All you have to do is group them into smaller numbers with brackets (). For example 3 + 9 + 1 can be bracketed together to make (3 + 9) + 1 or 11 + 1. Back to the original question, 3 + 9 + 2 + 4 + 3 + 4 + 5 can be bracketed as (3 + 9) + (2 + 4) + (3 + 4) + 5 or 11 + 6 + 7 + 5. Bracket it again to (11 + 6) + (7 + 5) or 17 + 12 which leads us to our final answer of 29. Bracketing helps separate each part of the equation into smaller more manageable parts and serves to organize portions of the problem to make it easier to keep your place. It's all about making it easier to read. Hope this helps!(8 votes)

- what is 56+67+89=(4 votes)
- To do this, we just have to group the places together, and then add them up individually:

56 + 67 + 89 = 50 + 6 + 60 + 7 + 80 + 9

= (50 + 60 + 80) + (6 + 7 + 9)

= (110 + 80) + (13 + 9)

= 190 + 22

= 192 + 20

= 212(6 votes)

- what is desimet times digit(10 votes)
- 5+6=11 and 11+3=14 and 7+7=14 and 8+6=14.(5 votes)
- Basically, to do any hard or easy math problem, you need to know how much the addition of any two numbers would equal to get it correct.(2 votes)
- Yep. Otherwise you won't be able to solve problems(2 votes)

- He said there are certain addition problems that you should know off the top of your head? what are all of them so I can memorize?(1 vote)
- Usually, it helps to memorize the additions and subtractions of all the numbers between 1 and 10. If you can memorize these, then it will help a lot when you do addition and subtraction problems with larger digits.(4 votes)

- what do you mean by add them at the same time becuase that is what im doing is adding them at the same same time but I dont know if im doing the right thing right over and over again(2 votes)
- I got it thanks sal khan(2 votes)

## Video transcript

- [Voiceover] So we have
three different shapes. We have stars, we have
squares and we have triangles. Now we have a different
number of each shape. So we have five stars,
we have three squares and we have six triangles. You don't see them all here. This is just telling us how many of each of these shapes that we have. So we have five stars, three
squares and six triangles, how many total shapes do we have? Well, you're probably saying, maybe I should add these numbers, because I'm trying to find
the total number of shapes. And if you said that I
would say you are right. So let's add those numbers. So we want to add five plus three plus six. So what is this going to be? Well what's five plus three, five triangles plus three squares. Well five plus three is eight, so this is going to be eight and then we still have to add six. So we're still going to add six. Now what's eight plus six? Well you may or may not know this, and if you don't this, well you could count
things out if you like, but it is a good thing to know just off of the top of your head. So if you don't know it yet, put this in your brain. Eight plus six is 14. Eight plus six is equal to 14. So five plus three plus
six is also equal to 14. Now one question you might have is, well does it matter the
order that I do this in? Well let's try it the other way around. Let's try it again. Let's try five plus three plus six. Instead of adding the
five and the three first, let's add the three and the six first. So what is three plus six? Well that's going to be nine. Then we're going to have five plus nine. Five plus nine. Well, once again, if you know
that, you'll know it's 14, If you don't know that,
that's another good thing to put in your brain and just to know. Five plus nine is equal to 14. If you don't know that, and you don't believe me take some pebbles out and five pebbles and then nine more, and you'll see that when you add them
together, you get to 14. But this is just a good thing
for you to know in your brain. And you could have done
it the other way around. You could have added five and six first, you get 11 plus three
would have also been 14. Either way, you have 14 total shapes.