Multiplying and Dividing of Fractions

Section 3.4 Pages 123 – 129

Section 3.5 Pages 130 – 136

Quick Review

When we multiply or divide two rational numbers we must always be aware of the signs of the two numbers.

Positive (x or ) positive = positive

Positive (x or ) negative = negative

Negative (x or ) positive = negative

Negative (x or ) negative = positive

This would be a good chart to copy down!

Reminder:

1

2

1

2

1

21

2

1

2

Multiplying Simple Fractions- Finding the Product

To multiply two simple fractions, complete the following steps. 1. Multiply the numerators. 2. Multiply the denominators. 3. Reduce the product. 4. Identify the resulting sign on the question

( -/+)

5. Reduce to lowest terms!!!

3 2

5 3

Example 3 2

5 3

6

15

2

5

Try ME:

5

12

2

9

8

12

4

7

Multiplying a Whole Number and a Fraction – Finding the Product

To multiply a whole number and a fraction, complete the following steps. 1. Convert the whole number to a

fraction. 2. Multiply the numerators. 3. Multiply the denominators. 4. Reduce the product. 5. Identify the resulting sign ( -/+)

Try ME:

2 3

4

7

8 3

What about mixed numbers?

If a question contains a mixed number, simply convert it to an improper fraction and… 1. Multiply the numerators. 2. Multiply the denominators. 3. Reduce the product. 4. Identify the resulting sign ( -/+)

Try ME:

62

3

15

6

22

5

35

9

Multiplying Rational Numbers in Decimal form

1. Predict the sign ( +/-)

2. Using compatible numbers to solve the question

3. Place the correct number of decimal places into your product

Try ME:

(-0.4)( -0.7) (0.5)(- 2.4)

Dividing Simple Fractions- Find the Quotient

To divide one fraction by a second fraction, convert the problem to multiplication and multiply the two fractions. 1. Change the second fraction to its

reciprocal 2. Multiply the numerators. 3. Multiply the denominators. 4. Reduce the quotient. 5. Identify the sign result of the question

(+/-)

What is a reciprocal?

Reciprocal The numerator and denominator are switched.

OR the fun way to remember it…

What is a reciprocal?

4

5

5

4

Reciprocal:A fraction doinga handstand!

Try ME:

3

2

6

7

7

9

9

4

Dividing Fractions with Mixed Numbers

To divide a fraction by a whole number: 1. Convert the mixed number to an

improper fraction. 2. Change the second fraction to the

reciprocal 3. Multiply the numerators. 4. Multiply the denominators. 5. Reduce the quotient. 6. Identify the sign result of the question

(+/-) Just like in multiplication, convert all mixed numbers to improper fractions

before dividing!

Try ME:

33

5

2

5

6

6

1

2

2

9

10

Pg.127-129 1,2,7,9,11,12,14,16

Pg.134-136 3,9,12,14, 21

Homework

See the Worksheets that accompany these sections.