Rounding Fractions to the Nearest Whole Number: Lesson for Kids

Instructor: Laurie Smith
Rounding normally isn't too difficult. However, if you are rounding fractions to the nearest whole number, how do you know whether to round up to the next number or down to the previous number? This lesson is going to explain it.

Backseat Problems

While they were on a long trip, Sarah and Charles were riding in the backseat of the car and getting bored. They drew an imaginary line down the center of the seat. ''Mom,'' said Sarah, ''Charles is on my side. He's got the whole thing!'' ''No, I don't,''said Charles, ''She's on my side, and I don't have any seat at all.'' Did they really have almost no seat or almost all of it? How can you tell?

How Much Is Half?

When it comes to a back seat - or even a pizza - we know what one-half is. But look at this first diagram. All three of the circles have one-half of the circle a different color. The first is 1/2 , the second is 2/4, and the third is 4/8. How can all these be one-half?

If you look, you can see the numerator, which is the top number, is half of the denominator, the bottom number. That is how you know a fraction is equal to one-half. It may be easier for some to think if the denominator is twice the numerator, then it is half. Either way is fine. Some other examples of fractions equal to one-half would be 50/100, 7/14, and 6/12. There are many fractions that equal one-half. See if you can find five others.

More or Less Than Half

It is pretty easy to determine if a fraction is more or less than one-half. If you know that 4/8 is equal to one-half, then 6/8 is more than one-half and 3/8 is less than one half. Look at this next diagram. An easy way to know if a fraction is more than half is if the numerator is more than half of the denominator. In the diagram, the blue section is 6/8.

Since you know how to tell what fraction is more than one-half, let's try to find if you can figure out how to see if a fraction is less than one-half. Would 2/8 be less than half? Well, the numerator is less than half of the denominator, (that would be 4) so 2/8 is less than half. In the diagram, the white part is 2/8.

Do You Round Up or Down?

Let's say you're counting along and you see a green line at 4¾. Is 4¾ closer to 5 or 4? Well, since you know that 2/4 is one-half, then 3/4 is more than half. It is closer to 5 than it is to four, so you would say 4¾ rounds off to 5.

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