Divide Using Models and Multiplication Facts

So in this first problem, it states that Joe and two other students are studying the moons of Uranus. Each student studies the same number of moons. Uranus has 21 known moons. How many moons does each person study?

So from this problem, we know that there are three students studying moons. We have Joe and two other students. So, we have three students studying. We also know that Uranus has 21 moons. So, we need to find the number of moons studied by each student. All right, so there is equal number of moons studied by each student. We know that from the problem that each student studied the same number of moons. So, we know the equal number of moons studied by each student. Since there are 21 moons and the total number of students is three, each student studies (21/3) moons.

So, (21/3) is going to equal the number of moons studied by each student. So, let's make a model to divide 21 by three. So here, we’re going to use 21 counters. So, we have 21 counters to represent the number of moons. Then, we’re going to use three groups to represent the three students. So our three groups represent the three students.

Now, we’re going to place one counter in each group. So here, I've placed one counter from each group. Now, the counters left are the (21/3), so now I have 18 counters left. Now, I'm going to continue placing one counter in each group until all are used. So, I went ahead and just kept moving counters in each group until all the counters are used. Now, I need to count the number of counters in each group. So, if I count the number of counters in each group, I have one, two, three, four, five, six, and seven. There are seven counters in each group. So, I have seven counters in each group.

So, the number of counters in each group represents (21/3), our original problem. So, the number of counters represents (21/3). So, the total number divided by the number of groups is equal to the number in each group. So therefore, 21 the total number divided by the number of groups which was 3 is going to equal seven, the number in each group. So, each student studied seven moons. We can also divide by four using models in the same way.

Let's move on to our second problem. Here we have Era. Era has 254 pictures of Jupiter. She gives the same number of pictures to four friends. How many pictures does each friend get? So, we know that four friends get the same picture. We also know that Era has 24 pictures of Jupiter. So, what we need to find is the number of pictures each friend gets. That’s what we’re looking for.

So, each friend gets the same number of pictures. We got this from the problem. So, each friend gets the same number of pictures. Since there are 24 pictures and the total number of friends is four, each friend gets (24/4) pictures. So each friend will get (24/4) pictures. So, (24/4) will give us the number of pictures each friend gets.

All right, so once way to divide 24 by four is to use models. Another way is to use multiplication facts. So, let's go ahead and use multiplication facts on this. So, we’re going to use multiplication facts to divide 24 by four. So, let's consider four groups of 24 objects. So, we need to divide 24 into four equal groups.

So, if we have (24/4), we need to divide 24 into four equal groups. So, we know that the number of groups times the number in each group will equal the total number or we know that (4*N) will equal 24. N being what we don’t know, the number of pictures each gets, the number in each group.

So, (4*N=24). So, now we need to think four times what number equals 24? Well, we know that (4*6=24). So, that means N has to equal six. Now, let's look at this again. So now we know that the number of groups is four, the number in each group we know is six and the total number is 24. So, let's go back to our original division problem. Now our division problem would be the total number which we know is 24 divided by the number of groups which is four, four is the number of groups and that will be the number in each group which we know now is six. So, (24/4) is six. So, each friend has six pictures of Jupiter.

Remember that we can also divide by three using related facts in the same way. All right, thing to remember and to keep in mind is that we can use models. We can divide by three using models by making three groups. To divide by four using models, we would make four groups. So for example, to divide (21/3), we use 21 counters and make three groups and we placed equal counters in each group. The number of counters represents (21/3). Remember that the total number divided by the number of groups equals the number in each group.

Also keep in mind that with multiplication facts, that the number of groups times the number in each group is equal to the total number.