Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.

Video: Arranging Mixed Numbers in Descending Order

Tim Burnham

Arrange the numbers on the cards in descending order.

02:50

Video Transcript

Arrange the numbers on the cards in descending order: one and five-eighths, two and one-sixths, one and five-sevenths, and one and two-fifths. Now the first thing to do is to think about what does descending mean. Well, you descend down the stairs; it’s going down. So we’re starting at the biggest thing and we’re ending up at the smallest thing.

So let’s create some slots for our answers; the largest is gonna go first and the smallest is gonna go last. Now the first number is one and something, the second number is two and something — so that’s obviously bigger than the first card — the third is one and something, and the fourth is one and something. So card number two here seems to have the biggest number. Two is bigger than one; so that’s definitely the biggest number. Now the other three cards are all one and something. So we need to look at the something — the fractions that go with the one, that are added onto the one — and see which is the largest and which is the smallest.

Well, five-eighths is over a half because four-eighths would be a half; so five-eighths is greater than a half. And five-sevenths, well three and a half sevenths would be a half, even though we shouldn’t mix fractions within fractions, but five-sevenths is bigger than three and a half sevenths. So five-sevenths is also bigger than a half. Well, that hasn’t got us very far so far. But let’s look at the last fraction and one and two-fifths. For two-fifths, two and a half fifths would be a half. So two-fifths is less than a half. So the first card is one and more than a half; the third card is one and more than a half. But the last card, the fourth card, is one and less than a half. So of those three, that must be the smallest card. So one and two-fifths is the smallest.

So now we got to evaluate these two things here: five-eighths or five-sevenths. Which is bigger and which is smaller? And to compare five-eighths and five-sevenths, we’re gonna take two identical circular cakes and cut them up into either eight pieces or seven pieces. Now if we were going to be sharing the same cake out between eight people, each person is gonna get a little bit less than they will get if we were sharing it out with seven people.

So five of the smaller pieces has got to be smaller than five of the larger pieces. So this means that one and five-eighths is smaller than one and five-sevenths. So there’s our answer: the largest number is two and a sixth, the next largest number is one and five-sevenths, the next largest number is one and five-eighths, and the smallest number is one and two-fifths.