Custom Search

Help with subtracting fractions

Subtracting and adding fractions are very similar. The only difference is the actual subtraction operation. All the steps that come before the operation are the same. However, as with addition and other math operations be sure to show and explore the concept using graphics and, if possible, hands-on exercises.

Subtracting fractions with the same denominator

Ensure your child can subtract fractions with the same denominator before tackling subtraction with different denominators.

To subtract fractions with the same denominator, subtract the numerator and keep the denominator.

Subtracting unlike fractions with different denominators

As with addition, the most important step in subtracting unlike fractions (fractions with different denominators) is finding a common denominator.

A common denominator can always be found by multiplying the denominator although this denominator will not always be the lowest common denominator.

Finding the lowest common denominator can be a trial and error exercise. Take the highest denominator, multiply it be 1, then by 2 ,then by 3 and so on. Each time check to see if the other denominator(s) are also divisors of the number.

Reduce the answer to its lowest term

It is good practice to finish by reducing the answer to its simplest form (lowest term) if it is not in that form already.

Be sure your child understands that an answer that is not in its simplest form is not necessarily wrong.

Worksheets

Use the worksheets below to practice subtracting fractions.

• Subtracting Fractions (same denominator) e.g. 4/7 - 2/7
• Subtracting Mixed Numbers (same denominator) e.g. 4 5/9 - 6 2/9
• Subtracting Fractions (different denominator) e.g. 2/3 - 1/4
• Subtracting Mixed Numbers (different denominator) e.g. 6 1/8 - 6