A person wants to distribute 30 notebooks equally into six bags. How many notebooks should they put in each bag?
The person described in this problem starts off with 30 notebooks. We’re told that they want to distribute them or share them out equally into six bags. This, then, is a division problem. We need to calculate the answer to 30 divided by six. Now, there are several ways we could do this. One is to think of a times table fact involving six and 30 that might help us. Another is to see how many sixes there are in 30 by using repeated subtraction. Let’s use this method to solve the problem.
Here are our 30 notebooks. And let’s use these ovals to represent the six bags that we’re going to share 30 notebooks into. So we’re going to repeatedly subtract six and put one more notebook in each bag at every time. And we’ll see how many sixes there are in 30. Or in other words, if we share 30 equally into six groups, how many will there be in each group? Let’s subtract our first lot of six.
So now, we’ve put one notebook in each group; 30 take away six equals 24. So we’ve got 24 notebooks left. Let’s subtract another lot of six. Now, we’ve subtracted two sixes. Each group has two notebooks. 24 take away six equals 18. So they’re 18 notebooks left. Let’s subtract another group of six. We’ve now subtracted three groups of six, and there are three notebooks in each group. 18 take away six equals 12. And we can see how many sixes we can continue to subtract from 12. In fact, can we notice something about each number? 30, 24, 18, 12. They’re all multiples of six. So if we subtract another lot of six, like this, we’ll only be left with six to subtract.
We could subtract six from 30 five times before we reach zero. This shows that 30 divided by six equals five. And the multiplication that we were talking about at the start of the video is six times five equals 30. If we’d have known that, we could have used it to help us find the answer. Instead, we used repeated subtraction. And so if the person wants to distribute 30 notebooks equally into six bags, they’ll have five notebooks in each bag.