Multiplying & Dividing
with Decimals~

The sixth chapter of the fifth grade math book focuses on multiplication and division of decimals. The standards for chapter 6 are:

Chapter 6

Number Sense: Multiply and divide decimals.

Number Sense: Demonstrate proficiency with division, including division with positive decimals.

Algebra and Functions: Use a letter to represent an unknown number; write and evaluate simple algebraic expressions in one variable by substitution.

Mathematical reasoning: Make decisions about how to approach problems.

Mathematical reasoning: Use a variety of methods, such as words, symbols, charts, tables, diagrams, and models, to explain mathematical reasoning.

Mathematical reasoning: Analyze problems by identifying relationships, distinguishing relevant from irrelevant information, sequencing and prioritizing information, and drawing patterns.

Mathematical reasoning: Make precise calculations and check the validity of the results from the context of the problem.

This chapter connects with previous and future learning in this way:

Looking Back	Right Now   Multiplying and Dividing Decimals	Looking Ahead
In chapters 4 and 5, students learned how to multiply and divide whole numbers.	In this chapter, students will learn to multiply and divide decimals.	In chapter 8, students will learn how to multiply and divide fractions.

The chapter has three sections of problem solving where the students are introduced to new strategies or are asked to apply previously learned concepts in new problems. The strategies for the fourth chapter are:

Multistep Problems pages 220-221

Choose a Strategy pages 228-229

Using Operations pages 240-241

In addition to the practice opportunities on this webpage, there are many links to math websites beyond this page to help you practice many math topics!

Time to Practice!

The Highview scout troop is planing a summer camping trip. The scouts buy their equipment on sale at Kauffman's Kamper World. Use a calculator to help them find the cost.

Item	Regular Price	Sale Price
Tent Stove Backpack Boots Sleeping Bag Pad	$249.95 $36.99 $79.50 $67.85 $162.50 $37.95	$224.95 $30.55 $65.25 $52.80 $143.95 2 for $65.00

What two items can be purchased for about $100.00 at the sale price?

What is the cost of 10 pairs of boots on sale?

Estimate the cost of 1 stove, 6 sleeping bags, and 6 pads at the sale price.

A parka regularly sells for $59.99. Estimate its sale price if marked down similar to the stove.

About how much will the scouts save on 8 backpacks and 12 pairs of boots?

The scouts paid for a stove and backpack on sale with five $20 bills. How much was the change?

What is the sale price per pad?

What three items have an average sale price of about $50.00?

If the sales tax is $0.06 on each dollar, what is the total cost of one sleeping bag?

What is the total cost of 3 pairs of boots and 2 tents, including a $0.06 sales tax on each dollar?

Take your pick!

Use mental math, pencil and paper or a calculator to solve each of the following in the most efficient way.

$32, 498 + $17, 120 = n

10 x $28.32 = x

$48.50 divided by 2 = a

$50 - ( $18.25 = $1.75) = s

$195.62 - $147.69 = p

$25 = ($37 - $12) = b

Complete the chart and find the pattern:

X	2	0.2	0.02	0.002
6
2
4
5
12

Estimation Practice~

Estimate the following products by rounding each factor to the nearest whole number:

15.3 x 2.8 ~ n

24.8 x 3.2 ~ p

7.2 x 19.7 ~ m

3.6 x 25.4 ~ b

39.6 x 5.9 ~ z

12.2 x 4.1 ~ x

Estimate and then decide which is the correct product:

2.68 x 42.7 = n	Is n = 114.36 or 1,114.36 ?
0.5 x 14.8 = n	Is n = 0.740 or 7.4 ?
0.92 x 4.5 = n	Is n = 4.140 or 41.4 ?
5.3 x 12.07 = n	Is n = 63.971 or 639.71 ?
4.87 x 72.1 = n	Is n = 35.1127 or 351.127 ?
76.2 x 41.4 = n	Is n = 315.468 or 3, 154.68 ?
176.5 x 4.1 = n	Is n = 72.365 or 723.65 ?

Complete these practice problems:

X	0.5	2.6
0.9
3.8
14.2
76.5
34.7
15.23
10.06
13.48
12.75

Complete this chart:

Percent	Decimal	Fraction
25%
50%
10%
5%
1%
20%
53%

Time to be challenged!

The product of two numbers is 90. One number is 2.5 times as great as the other. What are the two numbers?	Ms. Sanchez fills the vending machines at Heights Motel. Every Monday she fills the soft drink machine. She fills the snack machine every third day. She fills the coffee machine every fifth day. She fills all three machines on Monday, August 3. What is the next date on which she will fill all three machines?   Have an old calendar around?
These are zoinks: 242; 143; 132; 484; 561; These are not zoinks: 450; 144; 133; 494; 566 What makes a zoink a zoink? What two digit number are all zoinks a multiple of?	At Bev's birthday party, 10 of her friends wore party hats and 8 of her friends used noisemakers. There were 12 guests. How many of her friends wore a hat and used a noisemaker?

Tutorials, explanations and practice

Practice decimal problems online from aaamath.com

Multiplying Thousandths by Tenths

Multiplying Thousandths by Hundredths

Multiplying Thousandths by Thousandths

Dividing a Decimal by a Whole Number

Dividing a Decimal by a Decimal-I

Dividing a Decimal by a Decimal-II

REVIEW: Decimal Place Values

REVIEW: Rounding Decimals to the Nearest Tenth

REVIEW: Rounding Decimals to the Nearest Hundredth

 

 

Time to Exercise the Brain~

Escape from Knab	Climb Math Mountain	Puzzler Archive
Puzzler	The Train Race	Online Mankala
Who Wants to Win $1,000,000.00?	Grade Five Problems	Family Math Challenges
What's the Best Way to get Paid?	Mystery Math	Coin Flipping

to Helpful Math Sites in General

Great Help for Most of Chapter 1	Need help? Ask Dr. Math
Practice rounding with online flashcards	Math Dictionary for Kids
Online Flashcards-all operations	Tons of chances for practice-worksheets
Totally Tessellated	A+ Math Games
Runaway Math Puzzles	Late Delivery-Great Algebra Practice
Mystery Math-How do they do that?	Order of Operations
Puzzler	Math Baseball
Multiplication tips by kids	Exponent Basketball
The Fruit Game	Math Playground