Solving multi-step problems (division): cookies
About this video
A bakery packs 144 cookies equally into 9 boxes, and Sindy buys one box and eats 5 cookies. The video divides first (144 / 9 = 16 cookies per box) using long division, then subtracts 5 to find Sindy has 11 cookies left.
You'll be able to
- decide to divide first and then subtract in a two-step word problem.
- use long division to find 144 / 9.
- explain what each step of my answer means in the story.
Key words
- equally
- So that every group gets exactly the same amount.
- long division
- A written way to divide big numbers one place at a time.
- remainder
- What is left over after dividing; here there is none.
Transcript
- [Instructor] We're told a bakery bakes 144 cookies and packs them equally into nine boxes. Sindy buys one of the cookie boxes and eats five cookies. How many cookies are left in Sindy's box? Pause this video. Have a go at that before we do this together. All right, so my brain wants to first figure out how many are going to be in each box, and then I'm gonna take away the five cookies that Sindy has eaten, and then we know how many are left.
So to figure out how many are in each box, we'd wanna take the total number of boxes, 144, and then it's divided equally into nine boxes. So, if we divide this by nine, then we know how much is in each box. So lemme write that, number in each box. So we'd wanna do that first.
And once we figure out the number in each box, that would also be the amount that Sindy gets when she buys one of the boxes. And then she eats five cookies, so then eats five cookies. So we'd subtract five from that, and we would know how many cookies are left in Sindy's box.
So let's first calculate what 144 divided by nine is, and we'll do a little bit of, I'll call it light long division here. So nine goes into 144, 144. It doesn't go into one, but it does go into 14. It goes into 14, lemme just use another color, one time, one times nine is nine.
We can subtract. 14 minus nine is five. Bring down that four. Nine goes into 54, six times exactly. Six times nine is 54, and we have no remainder. So it goes exactly 16 times. So 144 divided by nine, this is 16, so we're left with 16 minus five. So Sindy had 16 cookies in her box.
She eats five of them. So what is she left with? Well, 16 minus five is equal to 11. Sindy's left with 11 cookies.
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