Transcript Dazzling Decimals – Day 2

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=
.
1. List the following numbers from least to greatest.
5, 4.5, 4.23, 0.12, 4.75, 0.75
0.12, 0.75, 4.23, 4.5, 5
2. Solve the following:
2.345 + 56 + 0.45= 58.795
$1356.99 - $23.89=
$1333.10
You have 3 minutes to copy.
4 Steps to Multiplying Decimals
Step 1: Write the problem vertically.
Multiply starting to the right.
Step 2: Place a 0 in the partial
product. Multiply by continuing
with the next number to the
left.
324
424
17.48
X 5.6
10488
87400
424
17.48
X 5.6
10488
You have 1 minute to copy.
4 Steps to Multiplying Decimals
Step 3: Add the partial products.
324
424
17.48
X 5.6
10488
87400
+
97888
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.
324
424
17.48
X 5.6
10488
+ 87400
97.888
2-decimal places
1-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
Cost
Ice Skating
$4.75 per hour
Skate Rental
$5.50
✔For Understanding
• Go to your handout and
complete the Lesson Practicepage 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
Divisor
.2 12.64
Moved (swung)
the decimal point
1 place to the
right
Steps in Dividing Decimals
2. Move (swing) the decimal point in the dividend the same
number of places as the divisor.
.2 12.64
Moved (swung)
the decimal point
1 place to the
right
Dividend
Steps in Dividing Decimals –
Swinging Monkeys
.2 12.64
Steps in Dividing Decimals –
Swinging Monkeys
3. Place (swing) the decimal point in the answer lined up with
the decimal point in the dividend (on the roof).
.2 12.64
Steps in Dividing Decimals
4. Now, divide as usual!
2 126.4
Steps in Dividing Decimals
4. Divide the numbers. Make sure the decimal point stays
lined up.
63 2
2 126.4
12
6
6
4
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 Practicepage 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?
socks
Actual
Cost
$29.95
$45.92
$7.50
Our
Estimate
$30.00
$50.00
$8.00
belt
$28.36
$30.00
shirt
jeans
$100.00
Find the Totals
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 Practicepage 37 (1-4 only). You will
have 6 minutes.
Exit Ticket
1. Take out your computer.
2. Log onto
http://www.quia.com/profiles/ylewis26
3. Take the Exit Ticket Quiz titled
February 17_18_ 2011_ Decimals Exit Ticket
secret word: dazzle
4. There are other activities on this Quia Web site to
practice your decimals.