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Multiplying and Dividing Decimals Review

In this section we are going to review

multiplying and dividing decimals.

Algebra 1A by Gregory Hauca Glencoe

adapted from presentations by

Linda Stamper

(No Transcript)

Multiply decimals as you would whole numbers.

Then place the decimal point in the answer

(product). To do this, add the number of decimal

places in the numbers being multiplied (factors).

Ex.1

Multiply the decimals.

1. Rewrite the problem vertically.

2. Multiply.

Do NOT line up decimal points.

3. Place the decimal point in the product. Add

the number of decimal places in the factors.

Write decimal points clearly!

When you multiply with a decimal, you may have to

write one or more zeros to the left of the answer

before you can place the decimal point.

Ex.2

Multiply the decimals.

1. Rewrite the problem vertically.

2. Multiply.

3. Place the decimal point in the product. Add

the number of decimal places in the factors.

Class Practice

Ex.4

Ex.5

Ex.3

When you divide a decimal by a whole number, the

decimal point in the quotient goes directly above

the decimal point in the dividend.

Ex.1

divide the decimals.

1. Rewrite the problem in standard division

format.

2. Place the decimal point in the quotient,

directly above the decimal point in the dividend.

3. Divide.

Write decimal points clearly!

To divide with a decimal divisor, move the

decimal to make the divisor a whole number. Then

move the decimal in the dividend by that same

number of places.

Ex.2

Multiply the decimals.

1. Rewrite the problem in standard division

format.

2. Move the decimal in the divisor and the

dividend to obtain a whole number divisor.

3. Place the decimal point in the quotient,

directly above the decimal point in the dividend.

Then divide

Write decimal points clearly!

Class Practice

Ex.3

Ex.4

Multiplying and Dividing Fractions Review

In this section we are going to review

multiplying and dividing proper and mixed number

fractions.

Algebra 1A by Gregory Hauca Glencoe

adapted from presentations by

Linda Stamper

To multiply two fractions, multiply the

numerators to get the numerator of the product

and multiply the denominators to get the

denominator of the product.

Example

Ex.1

Multiply the fractions. Simplify answer.

1. Multiply numerators and denominators.

When multiplying fractions simplify any numerator

with any denominator before multiplying the

numerators and denominators.

Not this...

Do this...

Multiply the fractions. Simplify answer.

Ex.2.

1. Simplify first any numerator and denominator.

2. Multiply numerators and denominators.

Multiply the fractions. Simplify answer.

Ex.3

1. Simplify first any numerator and denominator.

2. Multiply numerators and denominators.

Do not simplify the two 3s. You may NOT simplify

two numerators together or two denominators

together.

When multiplying mixed number fractions first

change the mixed numbers to improper fractions.

Then multiply.

Multiply the fractions. Simplify answer.

Ex.4

1. Rewrite as improper fractions.

2. Simplify first when possible by reducing.

(Dividing by the Greatest Common Factor.)

3. Multiply numerators and denominators.

Multiply the fractions. Simplify answer.

Ex.5

1. Rewrite as improper fractions.

1. Rewrite as improper fractions.

2. Simplify first when possible by reducing.

(Dividing by the Greatest Common Factor.)

2. Simplify first when possible by reducing.

(Dividing by the Greatest Common Factor.)

3. Multiply numerators and denominators.

3. Multiply numerators and denominators.

Class Practice

Ex.7

Ex.6

Ex.8

Ex.9

When we multiply a fraction by a fraction we

multiply the numerators and the denominators to

get the resulting product.

To divide a fraction by a fraction we need to

change the fraction division to an equivalent

fraction multiplication.

We do this by multiplying the first fraction by

the reciprocal of the second fraction.

Example

Ex.1

Divide. Simplify answer.

1. Change the division to a multiplication and

the second fraction to its reciprocal.

2. Reduce first and multiply.

To divide mixed number fractions we need to first

convert the mixed numbers to improper fractions.

Then we follow the same steps we learned to

divide simple fractions.

Ex.2

Divide. Simplify answer.

1. Convert mixed numbers into improper fractions

2. Change the division to a multiplication and

the second fraction to its reciprocal.

3. Multiply and simplify.

Ex.3

Ex.4

Class Practice.

Ex.5

Ex.6

Ex.7

Homework

- HW1A5 Handout

Decimal/Fraction Review B

WHITEBOARD PRACTICE.

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