Dazzling Decimals – Day 2

February 18, 2011

Dazzling Decimals • Agenda

–Multiplying Decimals–Dividing Decimals–Estimating with Decimals

Let’s Go!

You will have 3 minutes to complete this warm-up. Use Your Dazzling Decimal Day 2 worksheet to Show Your Work.

1. List the following numbers from least to greatest.5, 4.5, 4.23, 0.12, 4.75, 0.75

2. Solve the following:2.345 + 56 + 0.45=

$1356.99 - $23.89=

You have 3 minutes to copy.

4 Steps to Multiplying Decimals

Step 1: Write the problem vertically. Multiply starting to the right.

4 2 417.48X 5.610488

Step 2: Place a 0 in the partial product. Multiply by continuing with the next number to the left.

You have 1 minute to copy.

4 Steps to Multiplying Decimals

Step 3: Add the partial products.

+

You have 2 minutes to copy.

4 Steps to Multiplying Decimals Step 4: Go back to the original problem and count the number of spaces after the decimal. Use that same number of spaces to place your decimal point in the answer.

+

2-decimal places1-decimal place

3-decimal places

Let’s Go!

Let’s Do this One Together!Use Your Worksheet to figure this out on your

own first. Then we will go over it together. Four friends went ice skating at the East End.

Two friends brought their own skates and did not have to rent. What is the total cost for the group of 4 to ice skate for 3 hours?

Ice Skating Rate

Item CostIce Skating $4.75 per hour

Skate Rental $5.50

✔For Understanding • Go to your handout and

complete the Lesson Practice-page 19 (1-6). You will have 10 minutes.

You have 2 minutes to copy the following notes:

Example One – Dividing with Whole Numbers

Step 1: Place the decimal point in the quotient. Focus on the red arrow.

Step 2: Ignore the decimal point and divide in the   same way you would divide whole numbers.

How to rewrite division problems?

13.44 ÷ 12 =

Let’s Get Down to Some Monkey Business!

Keep your eyes on the slides while your teacher explains.

Steps in Dividing Decimals

1. Make the divisor a whole number by moving (swinging) the decimal to the right as many places as it takes.

2. In MONKEY TERMS: Whatever the outside monkey does (how far it swings) the inside monkey does also. Then the monkey climbs up and sits on the roof!

Swinging Monkeys

64.122.Divisor

Moved (swung) the decimal point 1 place to the right

Swinging’

Monkey

Steps in Dividing Decimals

2. Move (swing) the decimal point in the dividend the same number of places as the divisor.

64.122. Dividend

Moved (swung) the decimal point 1 place to the right

Steps in Dividing Decimals – Swinging Monkeys

64.122.

Steps in Dividing Decimals – Swinging Monkeys

64.122.

3. Place (swing) the decimal point in the answer lined up with the decimal point in the dividend (on the roof).

Steps in Dividing Decimals

4. Now, divide as usual!

4.1262

Steps in Dividing Decimals

4. Divide the numbers. Make sure the decimal point stays lined up.

4.12626

126

2

64

3

You have 4 minutes to copy the following notes:

Example One – Dividing with a Decimal

Step 1: Move decimal point to right to make it a whole number and move decimal point in dividend the same number of places.

Step 2: Put decimal point directly above decimal point in the dividend.

Step 3: Divide as usual. Keep dividing until the answer terminates or repeats.

✔For Understanding • Go to your handout and

complete the Lesson Practice-page 31 (1-6). You will have 10 minutes.

Estimating with Decimals

• When it is not necessary to find an exact answer, you can find an estimate.

• Let’s go shopping. While we are shopping, I need to have you estimate with me.

• We have $100.00 to spend at the mall.

Will we have enough?

Actual Cost

Our Estimate

shirt $29.95 $30.00jeans $45.92 $50.00socks $7.50 $8.00belt $28.36 $30.00Find the Totals

$100.00

You have 4 minutes to copy the following notes:

Estimating with Decimals

Step 1: Round the numbers to the greatest place value.

Step 2: Solve the problem.

Jeff had $401.42 in his savings account. He withdrew $147.26. About how much money is Ieft in Jeff’s savings account?

$400.00−$150.00 $250.00

✔For Understanding • Go to your handout and

complete the Lesson Practice-page 37 (1-4 only). You will have 6 minutes.

Exit Ticket1. Take out your computer.2. Log onto http://www.quia.com/profiles/ylewis263. Take the Exit Ticket Quiz titledFebruary 17_18_ 2011_ Decimals Exit Ticketsecret word: dazzle4. There are other activities on this Quia Web site to

practice your decimals.