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## Arithmetic

### Course: Arithmetic>Unit 15

Lesson 4: Dividing fractions and whole numbers word problems

# Dividing fractions and whole number word problems

This video uses tape diagrams to visually represent division with fractions. It shows how to divide a fraction or a whole number into equal parts. Tape diagrams help us see the process in a clear, simple way.

## Video transcript

- [Instructor] We are told that Billy has 1/4 of a pound of trail mix. He wants to share it equally between himself and his brother. How much trail mix would they each get? So pause this video and try to figure that out. All right, now let's work through this together. So Billy starts with 1/4 of a pound of trail mix. So how can we represent 1/4? Well, if this is a whole pound, let's just imagine this rectangle is a whole pound, I could divide it into four equal sections. So let's see, this would be roughly two equal sections, and then if I were to divide each of those into two, now I have four equal sections. So Billy is starting with 1/4 of a pound. Draw a little bit, try to make it a little bit more equal. Billy is starting with 1/4 of a pound, so let's say that is that 1/4 of a pound that he starts with. He's starting with 1/4 of a pound, and he wants to share it equally between himself and his brother. So he wants to share it equally between two people right over here. So what we wanna do is essentially say, let's start with our total amount of trail mix, and then we're going to divide it into two equal shares. So when they ask us how much trail mix would they each get, we're really trying to figure out what is this 1/4 divided by two? So what would that be? Well, what if we were to take all of these four equal sections and divide them into two? So I'll divide that one into two. I will divide this one into two. I will divide this one into two, and then I would divide this one into two. And now what are each of these sections? Well, each of these are now 1/8. That's a 1/8 right over there, the whole is divided into eight equal sections. And so you can see, that when you start with that 1/4, and you divide it into two equal sections, so one section and two equal sections right over there, each of these is equal to 1/8. So 1/4 divided by two is equal to 1/8. Let's do another example. So we are told Matt is filling containers of rice. Each container holds 1/4 of a kilogram of rice. And then they tell us if Matt has three kilograms of rice, how many containers can he fill? So like always, pause this video, and see if you can figure that out. All right, so let's think about what's going on. We're starting with a total amount, three kilograms of rice, and we're trying to divide it into equal sections. In this case we're trying to divide it into equal sections of 1/4 of a kilogram. So we are trying to figure out what three divided by 1/4 is going to be equal to. Now to imagine that, let's imagine three wholes, this would be three whole kilograms. So that is one whole, this is two wholes, trying to make them all the same, but it's hand-drawn, so it's not as exact as I would like. So that's three whole kilograms here. And he wants to divide it into sections of 1/4. So if you divide it into fourths, how many fourths are you going to have? Well, let's do that. So let's see, if we were to divide it into halves, it would look like this. If you divide these three wholes into halves. But then if you want to divide it into fourths, it would look like this, I'm trying to get it as close to equal sections. They should be exactly equal sections. So I am almost there. So there you have it. So I've just taken three wholes and I've divided it into fourths. So how many fourths are there? Well, there are one, two, three, four, five, six, seven, eight, nine, 10, 11, 12 fourths. So three divided by 1/4 is equal to 12. And I encourage you to really think about why this is the case, that if we take a whole number like three and you divide it by 1/4, we're getting a value larger than three. And we're getting a value that is four times three. Think about why that is the case.