Multiplying Fractions Multiplying Fractions with Cross Cancellationwith Cross Cancellation

Cross Cancellation - Cross Cancellation - dividing a dividing a numerator and a denominator by the numerator and a denominator by the

same numbersame number

Cross Cancellation Cross Cancellation • Multiply 3 x 1 • 4 3 • Step 1. Look for the same number in

the numerator and denominator. 3 is in the numerator and denominator.

• Step 2. Divide the numerator and denominator by 3. Write the new numerator and denominator.

• Step 3. Multiply the new numerator and denominators.

• The Product of 3/4 times 1/3 is 1/4.

• Multiply. Use cross cancellation first.

• 1. 1/5 x 5/6• 2. 3/8 x 1/3• 3. 1/8 x 8/9• 4. 4/5 x 3/4

Remember! Remember!

You can use cross cancellation even when you do You can use cross cancellation even when you do not see the same number in the numerator and not see the same number in the numerator and denominator. Look for the other common factor.denominator. Look for the other common factor.

ExampleExample

Multiply 1 x 4 2 5

Step 1. Find a common factor of a numerator and denominator. 2 and 4 have a common factor of 2.

Step 2. Divide the denominator 2 and the numerator 4 by the common factor. Write the new numerator and denominator.

Step 3. Multiply the new numerators and denominators.

Sometimes you can cross-cancel more Sometimes you can cross-cancel more than once. You can cancel two times.than once. You can cancel two times.

Step 1. Find common factors of the numerators and Step 1. Find common factors of the numerators and denominators 3 and 15 have a common factor of 3, 6 denominators 3 and 15 have a common factor of 3, 6 and 10 have a common factor of 2.and 10 have a common factor of 2.

Step 2. Divide the numerators and denominators by Step 2. Divide the numerators and denominators by the common factors. Write the new numbers.the common factors. Write the new numbers.

Step 3. Multiply the new numerators and Step 3. Multiply the new numerators and denominators. denominators.