Adding and Subtracting Fractions

Fractions are parts of a whole. Sometimes, we need to add or subtract fractions that have different denominators. The denominator is the bottom number of a fraction. When denominators are different, we need to find a common denominator before we can add or subtract.

Think about adding 1/2 and 1/4. The denominators are 2 and 4. To find a common denominator, we can find a number that both 2 and 4 divide into evenly. In this case, 4 works well. We can change 1/2 into an equivalent fraction with a denominator of 4. To do this, we multiply both the numerator (top number) and the denominator of 1/2 by 2. So, 1/2 becomes 2/4.

Now we can add 2/4 and 1/4. We only add the numerators, so 2/4 + 1/4 = 3/4. The denominator stays the same.

Subtracting fractions with different denominators works the same way. First, find a common denominator. Then, change the fractions to have that denominator. Finally, subtract the numerators. For example, to subtract 1/3 from 1/2, we can use 6 as the common denominator. 1/2 becomes 3/6, and 1/3 becomes 2/6. Then, 3/6 - 2/6 = 1/6.