Applying Fractions

When are we going to use this?

• Cooking – cutting a recipe in half or double it.

• Construction – using blueprints

Multiplying fractions

• 1. Make mixed numbers into improper fractions.

• 2. Multiply numerators

• 3. Multiply denominators

• 4. Simplify fractions if needed.

Example

• 1 x 3 = 3x1 = 3

5 8 5x8 40

2 1 x 5 = 7 x 5 = 7x5 = 35 = 1 8

3 9 3 9 3x9 27 27

What happens to the numerator when we multiply fractions?

• 3 x 3 = 3x3 = 9

4 5 = 4x5 20

The numerator became larger.

What happens to the denominator when we multiply fractions?

• 3 x 3 = 3x3 = 9

4 5 = 4x5 20

The denominator became larger.

What happens to the answer when we multiply fractions?

• 3 x 3 = 3x3 = 9

4 5 = 4x5 20

The answer became smaller than both of the original fractions.

Describe the effects of multiplication on fractions.

• Multiplying fractions actually creates a smaller fraction.