Multiply fractions & mixed numbers

A fraction of an amount can be smaller than the amount. Use an area model to explain the product.

Your learning goal

Multiply positive fractions, mixed numbers and whole numbers, and justify the result with a model.

Understand the idea

Whole-number multiplication counts groups

Three groups of 2/3 is 3 × 2/3 = 6/3 = 2. The denominator stays 3 when counting repeated thirds. Writing the whole number as 3/1 makes the general multiplication rule visible.

Words worth knowing
Factor
A number being multiplied.
Product
The result of multiplication.
Area model
A diagram that represents multiplication using overlapping parts of a rectangle.
Common-factor simplification
Dividing a numerator and a denominator by the same factor within a product.
Make it visible

Find the overlap—and explain its unit.

Predict a result, change a value, and use the diagram to explain your reasoning.

Fraction A
Fraction B

Every outlined unit rectangle represents one whole. Dots identify the overlap; the controls support fractions and mixed amounts up to two wholes.

Fraction multiplication takes a part of a part

For 2/3 × 3/4, shade 2/3 of the width and 3/4 of the height of one rectangle. The overlap contains 6 of 12 equal small rectangles, so the product is 6/12 = 1/2 of the original whole.

Multiply numerators and denominators

The new unit parts come from both partitions: thirds by fourths make twelfths. Thus (a/b) × (c/d) = (a × c)/(b × d), with non-zero denominators. You do not need a common denominator first. Convert mixed numbers to improper fractions before using this rule.

Khan Academy
Watch · pause · explain

Multiplying fractions with an area model

Pause before the next step. Explain what the shaded region or group represents, then compare it with the model above.

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Simplify factors and predict the effect

In 4/9 × 3/8, divide 4 and 8 by 4, and 3 and 9 by 3, before multiplying: 1/3 × 1/2 = 1/6. This works because the entire numerator and denominator form one product. For a positive amount, multiplying by a number between 0 and 1 makes it smaller; multiplying by a number greater than 1 makes it larger.

Follow the reasoning

One decision at a time.

Work out the next step before opening the explanation.

Find 2/5 of 3/4 of a sheet
  1. Interpret “of” as multiplication: 2/5 × 3/4.
  2. A five-by-four partition contains 20 equal regions; the overlap contains 6.
  3. 6/20 = 3/10 of the original sheet. This is less than 3/4 because only part of that amount is kept.
Multiply 1 1/2 × 2 2/3
  1. Convert: 1 1/2 = 3/2 and 2 2/3 = 8/3.
  2. Multiply and simplify: (3 × 8)/(2 × 3) = 8/2 = 4.
  3. Check the size: one and a half groups of 2 2/3 is 2 2/3 + 1 1/3 = 4.
Try with support

Make your thinking visible.

Use paper or a whiteboard. Show the equal parts, calculation and explanation before comparing your response.

Multiply 3/4 × 2/9.

Give me a hint

Look for common factors across the product before multiplying.

Compare a worked response

1/6

6/36 simplifies to 1/6. You can simplify 3 with 9 and 2 with 4 first.

Find 3/5 of 20 litres.

Give me a hint

First find one fifth of 20, then count three fifths.

Compare a worked response

12 litres

20 ÷ 5 = 4 litres; 3 × 4 = 12 litres.

Independent practice

Build a strategy you can explain.

Fresh questions · useful feedback

Build fluency, one decision at a time.

Work through eight questions. Two independent correct answers introduce a harder version; supported answers bring the next question back to the foundation. You can use hints at any time.

0 of 8 questions completed

Use an exact fraction (7/12), mixed number (1 3/4), or terminating decimal. For comparisons use <, = or >. Follow any requested form; leave units out of the answer box.

This round saves on this device. It is practice, not a school mark.

Check the concepts, too.

1. What is 2/3 × 3/5?

2. What happens to a positive amount when multiplied by 1/4?

3. Which is a valid first step for 2 1/3 × 3/4?

Make it matter

What does the answer mean?

Scaling a recipe by 3/4 means multiplying every ingredient by 3/4. Changing only one ingredient does not preserve the recipe.

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