Add and Subtract Mixed Numbers
In this lesson, we will add and subtract mixed numbers.
The first step is to add the whole numbers which are shown in red. Then you can add the numerators. The denominator remains the same.
We have to rename the fraction by finding the LCD as we did in example 2. First, you will subtract the numerators and the denominator will remain the same and then subtract the whole numbers. Lastly, you need to reduce the fraction to simplest form.
Step 1.In order to add mixed numbers with different denominators we must find their LCD(least common denominator). The least common denominator is also the smallest whole number both denominators have in common. To find the LCD we have to find the multiples of each number.You can do this by mumultiplying the numbers by 2,3,4,5 etc...
2: 4, 6,8,10
3: 6, 9, 12
Notice the smallest whole number they have in common is 6. Step 2 we have to rename to fractions to have a denominator of 6. We will multiply 1/2 by 3 and 1/3 by 2.
To subtract a whole number from a mixed number we have to change the whole number to a mixed number:
After changing 7 to a mixed number, we need to find the LCD:
6: 6, 12
2: 4, 6
Once we have renamed the fraction to have a denominator of 6, we need to subtract the fractions first. Remember the denominator remains the same, just subtract the numerators.
Activity: Mixed Number Showdown
You can hold up a large piece of paper with a problem and the student who answers the problem first wins a prize or a homework pass. Repeat this several times with different problems of course.
Found on the Web:
Mixed Numbers- identify and define mixed number parts