Video: Solving Word Problems Involving the Division of Numbers up to 100

There were 15 birds on a tree, but a third of them flew away. Find the number of birds that flew away.

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Video Transcript

There were 15 birds on a tree, but a third of them flew away. Find the number of birds that flew away.

To begin with in this problem, we’re told about a group of birds. There were 15 of them on a tree. Let’s model our 15 birds using plastic counters. Now, we’re told that some of these birds flew away. And fortunately, we’re not told the number of birds that flew away. This is what we need to find. Instead, we’re told the fraction of the whole amount. This is a third. Now this is a third written in words. But do you remember how to write it using digits? The numerator is one. This shows us that we’re only thinking about one-third and not two-thirds or more. And then the denominator is three. This shows us the number of equal parts that we need to split the whole into.

So to find one-third of 15, we can divide 15 by the denominator, three. If we split 15 into three equal groups, how many will there be in each group? Perhaps you can think of a times tables fact that could help us here. We know that three times five equals 15. 15 divided by three equals five. And we can show this using our counters. We’ve split the whole amount into three equal groups, and each of the three groups, that’s each third, is worth five. So if there were 15 birds on a tree, but a third of them flew away, the number of bird that flew away is five.

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