How to Do Decimals & Fractions for a Fifth Grader

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Doing decimals and fractions for a fifth grader will begin with the concepts of addition and subtraction. Do decimals and fractions for a fifth grader with help from an experienced mathematics educator in this free video clip.

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Video Transcript

Hi, my name's Marija. And today, I'm going to show you how to do decimals and fractions for a fifth grader. So, beginning with decimals, if you're adding or subtracting decimals. The important thing to teach a fifth grader is that you have to line up the decimals when we add. So, the decimals have to be right on top of each other, otherwise it'll ruin your problem. So, when you add or subtract decimals, you add like you would two regular two digit numbers. Three plus four is seven, seven plus two is nine. And you bring down your decimal and that's it. So, we added the digits, we kept the decimal where it was and we got our sum. And it's going to be the same rule for subtraction. When you are multiplying decimals, here's what you have to remember. Let's say that I have seven point four times point two. You can ignore the decimals at first, and just multiply as you would a regular two digit by one digit. So, we would have two times four is eight and two times seven is 14. But now what you have to do is, count the total number of decimals that are in your problem. So in the top number I have one decimal space, and in the bottom number I have another decimal space. So, I have two total decimal spaces. Now, when you answer, what you have to do is go back the same number of spaces that were used. So, we have to go back, one, two and that puts my answer at one point four eight. So, that's how you add and subtract, multiply and divide decimals. Now, for fractions, if we're adding fractions, if they've got the same denominator. They'e got the same bottom number, then we can go ahead and keep that denominator and just add the numerators. So, one plus two is three and this becomes one. However, if they different denominators, like if we has one-third plus one-sixth. We would have to make the denominator the same first. So, we need a common denominator. So, what we're going to do is change this fraction, the one-third into a fraction that has a six as it's denominator. So, to get from three to six, I did times two. So, I'm going to have to do one times two to get two. So, my new fraction is two-sixths. Now, I can add two plus one is three, and I can keep the six just like I kept the threes in the top one. And I get three-sixths or one-half ad my answer. If you're multiplying fractions, you multiply straight across. So, if we had two-thirds times one-half, I would just multiply straight across. Two times one is two and three times two is six. And then, you can reduce this to one-third. And that is how you do decimals and fractions for fifth grade.


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