Module 1Test Review

Now is a chance to review all of the great stuff you have been learning in Module 1!

– Adding and Subtracting Decimals– Multiplying Decimals– Dividing Decimals– Division of Fractions– Division of Mixed Fractions

Place Value

In order to be able to add or subtract decimals you must be able to read the numbers according to place value.

Place Value

Let’s look at the place value of the digits in the number 65.483

If you line up the decimal with the word “and” then fill in your numbers you can quickly see the place value for each digit.

Estimation

• We can use estimation we can find an approximate amount.

One method of estimation is to round a number to a specific place value. You round a number by determining if the digit to the right of the specified place value is greater than or equal to 5. If it is greater than or equal to 5, you round the number up one digit. If the digit is less than 5, it remains the same

Example:

Using Estimation to Add or SubtractHow can we use estimation in this problem?Mary went to the video game store and bought three used games, which cost $9.57, $13.28, and $15.82. What was the total approximate cost of all three games if you round to the nearest dollar?

1. Round each number the nearest whole number $9.57 ≈ $10$13.28 ≈ $13$15.82 ≈ $16

2. Find the sum To find the sum, add up all the prices. The total is the sum.10 + 13 + 16 ≈ 39

What do you think?

 Which do you think is the correct way to find the sum of 47.62 and 12.3?

What do you think?

 Which do you think is the correct way to find the sum of 47.62 and 12.3?

As you can see, place value is very important when adding or subtracting decimals.

Adding Decimals

Adding Decimals

Determine the sum for the following: 5.439 + 3.2 =

1. 5.439 Line up the decimals by their place value.+ 3.2 If you can not drop a straight line through your decimal points you have not lined them up

correctly.

1. 5.439 Add zeros as place value holders+ 3.200

Add each column vertically starting with the smallest place value position 5.439+ 3.200 8 639Bring your decimal point straight down. 5.439+ 3.200 8.639

Subtracting Decimals

Subtracting Decimals

What is the difference: 74.8 − 35.12 =

Adding Decimals

What is the difference: 74.8 − 35.12 =

1. 74.8 Line up the decimals by their place value.- 35.12 If you can not drop a straight line through your decimal points you have not lined them up

correctly.

74.80 Add zeros as place value holders- 35.12

Subtract each column vertically starting with the smallest place value position 74.80- 35.12 74.80- 35.12 Bring your decimal straight down. 39.68

Caution – make sure if subtraction is not possible you use your regrouping skills to subtract

Multiplying Decimals – words to know

Multiplying Decimals

ExampleWhat is the product of 3.79 × 6.5?

Ignore the decimal and multiply as usual

Add the partial products

Division is used to spread large amounts into smaller groups.

Words to know:

Estimation with Division

Use estimation to find the approximate quotient of 12,330 ÷ 18.

Dividing Whole Numbers

Division with Models

Models can usually make a mathematical problem easier to tackle

Different types of Models

Double Bar Model Line Model Rectangular Cross Box Model

It is up to you which of the fraction models you would like to use.

Double Bar Model

Line Model

Rectangular Cross Box Model

Proper Fraction

a fraction that describes an amount less than one whole, where the numerator is less than the denominator

Improper Fraction

a fraction that describes an amount greater than or equal to one whole, where the numerator is greater than or equal to the denominator

Mixed Fraction

the sum of a whole number and fraction; a mixed number has a whole number part and a fraction part

Converting Mixed Fractions

Converting Improper Fractions

Dividing Mixed Fractions using the Reciprocal

Find the quotient of

Example

Dividing Fractions

Drawing models is one way to divide fractions. It can become difficult to draw all those models

A standard method you can use to divide fractions requires you to use the reciprocal of the divisor

What is a reciprocal?

Reciprocal

Dividing Fractions using the Reciprocal

1. Rewrite the problem (KSF)Keep the first fraction Switch the sign to multiplication

Flip the second fraction2. Use Cancellation if possible. 3. Multiply numerator times numerator 4. Multiply denominator times denominator 5. Check to see if the final answer is in simplest form

1. Rewrite the problem (KSF)Keep the first fraction

Switch the sign to multiplication Flip the second fraction

2. Use Cancellation if possible. 3. Multiply numerator times numerator

4. Multiply denominator times denominator 5. Check to see if the final answer is in

simplest form

Sum it Up!

Sum It Up!

Example

What is the quotient of 16,800 ÷ 32?

ExampleWhat is the quotient of 8,587 ÷ 12?

Dividing with Decimals

Example147.2 ÷ 3.2 =

Sum it Up!

You have now had a chance to review all of the great stuff you learned in Module 5!

• Adding and Subtracting Decimals• Multiplying Decimals• Dividing Decimals• Division of Fractions• Division of Mixed Fractions

Have you completed all assessments in module 1? Have you completed your Module 1 DBA?

Now you are ready to move forward and complete your module 1 test. Please make sure you are ready to complete your test before you enter the test session.