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## Arithmetic (all content)

### Course: Arithmetic (all content) > Unit 3

Lesson 8: Relating multiplication and division# Multiplication word problem: parking lot

Sal uses a picture and repeated addition to solve a multiplication word problem. Created by Sal Khan.

## Want to join the conversation?

- why does the questin state theat each car has four wheels? Is the relevant to the completion of the question?(1 vote)
- No, it's not relevant to finding the answer to the question: that's the point! Listen to Sal at0:25, where he says that we don't have to care about how many wheels there are. One of the goals of this exercise is to teach the value of finding and using
*only*the relevant information, and ignoring things that aren't relevant.(4 votes)

- So you guys are saying that multiplication is the same as repeated addition, and division the same as repeated subtraction?(5 votes)
- It's tempting to say that division is repeated subtraction. If you view division this way, then you'll have to count how many times you've subtracted.(4 votes)

- hi guys what are you doing?(3 votes)
- If division is same to muiltipulcation is addition and subtraction the same(0 votes)
- No, addition is the opposite of subtraction and multiplying is the opposite of divison because: 8 × 8 = 64 and 64 ÷ 8 = 8 and 8 + 8 = 16 and 16 - 8 = 8 are true if they were not true then no math would work correctly.(10 votes)

- Why do the word problems include information that is never used?(2 votes)
- In the real world you will often have more information than you need to solve a problem. So word problems often have more information than necessary to help you practice figuring out what information is needed and what can be discarded.(5 votes)

- What if there were bigger numbers involved?(2 votes)
- It would still work, you need to learn another way to multiply- check out the other multiplication videos.(2 votes)

- jeez why are all the comments so old?(1 vote)
- the way you were able to figure out the multiplication answer using addition can all multiplication be done in the same manor to find the answer?(0 votes)
- All multiplication is a simpler way to do adding. So yes, all multiplication problems can be solved using adding. Sal used adding to show you the relationship between the two. Though multiplication will get much harder soon and you will find it easier to just multiply.(3 votes)

## Video transcript

The local grocery store opens at nine. Its parking lot has six rows. Each row can fit seven cars. Each car has four wheels. How many cars can the parking lot fit? And I encourage you to pause the video
and think about this yourself. Try to figure it out on your own. So, let's re-read this. The local grocery store opens up at nine. Well, that doesn't really matter. If we're thinking about
how many cars can the parking lot fit. So we don't really have to care about that. We also dont have to care about
how many wheels each car has. They're not asking us how many
wheels can fit in the parking lot. So we can ignore that. What we really care about is
how many rows we have. And how many cars can fit in each row. What we have is -- We have six rows
and each row can fit seven cars. We're going to six groups of seven. Or, another way of thinking about it. We're going to have six times seven
cars can fit in the parking lot. What is this going to be equal to? This is literally six sevens added up. This is the same thing as
one, two, three, four, five, six. That last seven looks strange. Now we're going to add these up. Seven plus seven is fourteen. Twenty-one, twenty-eight,
thirty-five, forty-two. Six times seven is equal to forty-two. So forty-two cars can fit in the parking lot.
Don't believe me? I made a little diagram here. We have six rows. This is the first row. Second.. Third.. Fourth.. Fifth.. Sixth. Each row can fit seven cars.
You see it here. One; Let me make that a little brighter. One.. Two.. Three.. Four, five, six, seven. How many cars are there? You have seven. Fourteen.. Twenty-one.. Twenty-eight.. Thirty-five.. Forty-two total cars. Six rows of seven.