Multiplying Fractions
Multiplying fractions means multiplying the numerators, then the denominators. Then simplify if you can. Cross-cancelling divides a top and bottom by a common factor first to keep numbers smaller.

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How Do We Multiply Fractions?
- Multiply the numerators together and multiply the denominators together.
- Then simplify the fraction, if possible.
What Is Cross-Cancelling When Multiplying Fractions?
- You can simplify first by cross-cancelling a numerator with a denominator.
- Cross-cancelling makes the numbers smaller and easier to multiply.
How Do We Multiply a Fraction by a Whole Number?
- Write the whole number as a fraction over 1.
- Then multiply as you would with two fractions.
How Do We Multiply Mixed Numbers?
- Convert mixed numbers into improper fractions first.
- Then multiply and simplify the final answer.
Practice Questions
Test your understanding
What is ?
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Multiply the numerators: . Multiply the denominators: .
So . The numbers 6 and 35 share no common factor, so this is already in its simplest form.
Notice the answer is smaller than both fractions: multiplying by a fraction less than 1 always makes a value smaller.
What is of 15?
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"Of" means multiply, so work out .
Find one fifth first: . Then multiply by the numerator: .
Using fractions throughout: write 15 as , cross-cancel the 5 with the 15 to leave 1 and 3, then over , giving 21. Since is bigger than 1, the answer is larger than 15.
What is ? Give your answer in its simplest form.
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Simplify each fraction first: (divide top and bottom by 5) and (divide top and bottom by 5).
Multiply the numerators: . Multiply the denominators: . So the answer is .
If you multiply without simplifying first you get , which cancels down to the same answer, .
What is ? Give your answer in its simplest form.
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Simplify each fraction first: 16 and 24 both divide by 8, giving ; 18 and 27 both divide by 9, giving .
Now multiply: for the numerator and for the denominator, giving .
Multiplying without simplifying first gives , which cancels down to the same answer, .
What is using the cross-cancelling method? Give your answer in its simplest form.
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Cross-cancel diagonally. The 25 and the 50 both divide by 25, becoming 1 and 2. The 40 and the 32 both divide by 8, becoming 5 and 4.
The calculation is now . Multiply: and , giving , which simplifies to .
Multiplying without cancelling gives , which cancels down to the same answer, .
What is using the cross-cancelling method?
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First change the mixed number into an improper fraction: .
Now cross-cancel: the 9 and the 3 both divide by 3, becoming 3 and 1. The calculation is .
Multiply: and , giving (which is ). Without cancelling you get , the same value.
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Interactive Activity
Master cross-cancellation across different formats
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Frequently asked questions
The questions students bump into most on this topic
Multiply the numerators together, then multiply the denominators together, and simplify if you can: 3/5 × 2/7 = 6/35. Unlike adding, you do not need a common denominator; the denominators can be different. Because the numbers grow quickly, it is easier to cancel common factors before you multiply, which is called cross-cancelling.
Cross-cancelling means dividing a numerator and a denominator by their highest common factor before you multiply, so the numbers stay small and the answer comes out simplified. For 11/24 × 36/55: 11 and 55 share 11, giving 1 and 5; 24 and 36 share 12, giving 2 and 3. Then 1 × 3 over 2 × 5 is 3/10.
Write the whole number over 1, then multiply as usual, cross-cancelling first if you can. A piano has 88 keys and 13/22 of them are black: 88/1 × 13/22. Cancel 88 and 22 by 22 to get 4 and 1, then multiply: 4 × 13 = 52 black keys. The method is exactly the same as for two fractions.
Change each mixed number into an improper fraction first, then multiply. A mixed number is a whole number plus a fraction, not a whole number times a fraction, so multiplying the parts separately gives the wrong answer. For 2 1/3 × 9/4: 2 1/3 = 7/3, cancel 9 and 3 to get 3 and 1, and 7 × 3 over 1 × 4 is 21/4, or 5 1/4.
Check every time. If you multiplied straight across, the answer often still has a common factor to cancel: 15/35 × 5/10 gives 75/350 that way, which simplifies to 3/14. If you cross-cancelled first, the answer is usually already in its simplest form, but it costs nothing to look.
What's next?
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