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O.2 Multiply two fractions: word problems

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What does it mean to multiply fractions?

Multiplying fractions means finding a part of a part. You multiply the top numbers (numerators) together and the bottom numbers (denominators) together to find the product.

Example:
  • 12 × 13 = 16
  • You multiply 1 × 1 = 1 and 2 × 3 = 6, so the answer is 16.
Note

Remember: multiplying fractions makes a smaller number because you are finding a part of a part.

Steps to multiply two fractions

Follow these steps to multiply two fractions correctly and simplify your answer when possible.

Steps:
  • Multiply the numerators (top numbers).
  • Multiply the denominators (bottom numbers).
  • Simplify the fraction if you can.
Note

Always check if your final fraction can be reduced to lowest terms by dividing both the numerator and denominator by their greatest common factor (GCF).

How to solve word problems with fraction multiplication

Word problems with fractions describe real-life situations where you find a part of a part, such as using part of a recipe or measuring a section of a garden.

Example:
  • Emily used 23 of a cup of sugar to bake cookies. She used 12 of that amount for chocolate chip cookies. How much sugar did she use for the chocolate chip cookies?
  • Multiply: 12 × 23 = 13
  • Emily used 13 cup of sugar for the chocolate chip cookies.
Note

Look for clue words like “of” or “part of” in the problem—these often mean you need to multiply fractions.

Mixed numbers in fraction word problems

Sometimes, a word problem will include mixed numbers. Before multiplying, change each mixed number into an improper fraction.

Example:
  • A board is 112 feet long. You need to cut 23 of it. How long is the piece?
  • Convert 112 to an improper fraction: 32
  • Multiply: 23 × 32 = 66 = 1
  • The piece is 1 foot long.
Note

Always simplify improper fractions and convert them back to mixed numbers when your answer is greater than one whole.

Check your answer

After solving a word problem, make sure your answer makes sense in the situation. A smaller result usually means you found a part of something.

Example:
  • If you multiply 12 × 12, the answer is 14. This makes sense because half of a half is one-fourth.
Note

Always reread the problem and check that your answer fits what the question asked. Use estimation to see if your answer seems reasonable.