## Total seats in a theater | Multiplication and division | 3rd grade | Khan Academy

A theater has a total of 63

seats in a rectangular grid. Here they are, right over here. It currently has 9 rows, each

with an equal number of seats. We see that– 1, 2, 3,

4, 5, 6, 7, 8, 9 rows. How many total

seats will it have if it adds 2 seats per row? So what we want to figure out

is the total number of seats. So let’s say that

the total is going to be equal to the

number of seats that the theater already has. And they tell us that they have

63 seats in a rectangular grid. So it’s going to be 63

seats plus the new seats, plus however many it adds. So plus the new seats. Well, what are the

new seats going to be? Well, the new seats are

going to be– I have 9 rows, and I’m adding 2 seats per row. So the new seats are going to

be 9 rows times 2 seats per row. So we could say

that the total is going to be equal to

63 plus 9 times 2. And we ‘ll talk more

about order of operations. But clearly, in

this situation, we want to multiply 9

times 2 to figure out the total new number of seats. And then we want

to add that to 63. And if we just

write it like this, multiplication takes– you

will always do multiplication. And when you just see

it in a row like this, you’ll do the multiplication

before you do the addition. So this is literally

saying, hey, multiply 9 times

2 first, then add to 63, which is exactly

what we care about. And what is 9 times 2? Well, let’s add those

2 seats per row. So that’s 2, 4, 6, 8,

10, 12, 14, 16, and 18. So 2 times 9. 2, 4, 6, 8, 10, 12,

14, 16, 18 is 18. So we’re adding 18 new seats. So let me write this down. I covered up my old total. So total is equal to 63 plus 18. I had 63 seats. I’m now adding 18 seats. So total– my total

number of seats– is now going to be 63 plus 18. Let’s see, 8 plus 3 is 11. 60 plus 10 is 70. 70 plus 11 is going to be–

I have 80– I have 81 seats. I now have 9 rows with 9 seats

each, which gets me 81 total.

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