Sunday, November 6, 2016

Adding Three or More Fractions





In this video you will learn to add three or more fractions with different denominators.

Transcript

Welcome to MooMooMath where we upload a ne Math video everyday. In this video I would like to work on adding more than one fraction. In particular adding three fractions. For instance, how would you add 1/2 + 1/3 + 3/4. We will start with an easy one.

I line the fractions up in a vertical line. Put 1/2 + 1/3 + 3/4 in a vertical line. I then find a common denominator for all three fractions. I know 12 will be the common denominator. I know 2 will go into 12 6 times and 6 x 1 =6 so we have 6/12. I keep them in this vertical line. 3 goes into 12 4 times and 4 x 1 = 4, and 4 goes into 12 3 times, and 3 times 9 = 9.

I next just add them up and when I add them I get 19/12

I then can convert to a mixed fraction by dividing 19 by 12 which equals 1 7/12.

Lets look at another example. Lets add 1/2 + 3/4 + 7/8

I line them up in a vertical column, and then I start thinking about a common denominator of 2.4.and 8. 8 will be the common denominator. 2 goes into 2 times, so we have 2/8's, oops 2 goes into 8 4 times.

Next 4 goes into 8 2 times and 2 times 3 = 6 and 8 goes into 8 1 time so that equals 7/8.

Next I add them, 4/8 + 6/8+7/8 = 17/8.

I have an improper fraction and 8 will go into 17 two times which is 16 and that leaves 2 1/8.

Let me go over how I created the mixed fraction.

17 divided by 8 equals 2 and 17 -16 =1 so it becomes 2 1/8

On this last one I have mixed fractions.

What if you have the following?

1 1/2 + 21/6 + 3 1/4

You can line them up vertically.

Lets line them up and you have, 1 1/2 + 2 1/6 + 3 1/4

Next you can add the whole numbers, and 1 + 2 + 3 = 6

and you will add the fractions. I'm going to rewrite them

1/2 + 1/6 + 1/4

Find a common denominator, which is 12, and 2 goes into 12 6 times, 6 goes into 12 2 times, and 4 goes into 12 3 times. I next add them up and I get 6 + 2 + 3 = 11/12

Now I combine these two and end up with 6 11/12, and I can't simplify anymore.

Thanks for watching and we upload a new Math video everyday.