Dividing a decimal by a whole number with fraction models

0:00- [Instructor] In this video, we're going to try to figure out what 4/10 divided by five is. So pause this video and see if you can think about it before we work through it together. We're really going to think about approaching this visually. All right, now let's work through this together.

0:17Let's actually try to think about what 4/10 looks like. So if you view this entire square as a whole, you see that we've divided it into 10 equal columns or 10 equal sections, and four of those tenths are shaded in, so what you see here in blue is 4/10. But how do we divide that into five and make sense of it?

0:41Well, one way to think about it is to imagine 4/10 not just as 4/10, but to imagine it as 40/100, so this would be imagining it as 40/100. So we can re-write 4/10 divided by 5 as 40/100 divided by 5, and now we can think about taking these 40 hundredths, each of these little squares is a hundredth, and divide it into five equal sections, and then we can say, well, how many hundredths are in each of those five equal sections?

1:17So let's do that. So let's see, this is one, this is two, this is three, this is four and then we have five equal sections. So how many hundredths are in each of those equal sections? Well we can see in each of them you have one, two, three, four, five, six, seven, eight.

1:42So 40/100 divided by five is going to be 8/100, because we have eight of these little squares in each of those five equal sections. So 8/100 we would like this. And so 40/100 divided by five is 8/100, then 4/10 divided by five is also equal to 8/100.