Fractions

Solving addition problems with fractions

Now that we know how to write addition problems with fractions, let's practice solving a few. If you can add whole numbers, you're ready to add fractions.

Click through the slideshow to learn how to add fractions.

• 

  Let's continue with our previous example and add these fractions: 3/5 of cup of oil and 1/5 of a cup of oil.

• 

  Remember, when we add fractions, we don't add the denominators.

• 

  This is because we're finding how many parts we need total. The numerators show the parts we need, so we'll add 3 and 1.
  
  

• 

  3 plus 1 equals 4. Make sure to line up the 4 with the numbers you just added.

• 

  The denominators will stay the same, so we'll write 5 on the bottom of our new fraction.

• 

  3/5 plus 1/5 equals 4/5. So you'll need 4/5 of a cup of oil total to make your cake.

• 

  Let's try another example: 7/10 plus 2/10.

• 

  Just like before, we're only going to add the numerators. In this example, the numerators are 7 and 2.

• 

  7 plus 2 equals 9, so we'll write that to the right of the numerators.

• 

  Just like in our earlier example, the denominator stays the same.

• 

  So 7/10 plus 2/10 equals 9/10.

• 

Now it's your turn! Try solving some of the addition problems below.

Solving subtraction problems with fractions

Subtracting fractions is a lot like regular subtraction. If you can subtract whole numbers, you can subtract fractions too! 

Click through the slideshow to learn how to subtract fractions.

• 

  Let's use our earlier example and subtract 1/4 of a tank of gas from 3/4 of a tank.

• 

  Just like in addition, we're not going to change the denominators.

• 

  We don't want to change how many parts make a whole tank of gas. We just want to know how many parts we'll have left.

• 

  We'll start by subtracting the numerators. 3 minus 1 equals 2, so we'll write 2 to the right of the numerators.

• 

  Just like when we added, the denominator of our answer will be the same as the other denominators.

• 

  So 3/4 minus 1/4 equals 2/4. You'll have 2/4 of a tank of gas left when you get home.

• 

  Let's try solving another problem: 5/6 minus 3/6.

• 

  We'll start by subtracting the numerators.

• 

  5 minus 3 equals 2. So we'll put a 2 to the right of the numerators.

• 

  As usual, the denominator stays the same.

• 

  So 5/6 minus 3/6 equals 2/6.

• 

Now you try it! Try solving some of the subtraction problems below.

After you add or subtract fractions, you may sometimes have a fraction that can be reduced to a simpler fraction. As you learned in Lesson 2, it's always best to reduce a fraction to its simplest form when you can. For example, 1/4 plus 1/4 equals 2/4. Because 2 and 4 can both be divided 2, we can reduce 2/4 to 1/2.