Transcript Document

How do you multiply
7 x 0.15?
In this lesson you will learn
how to multiply decimals by
whole numbers by using an
area model.
Let’sReview
Review
Let’s
Ones
1 group of 100 =
100
2 groups
of ten =
20
Ones
3 single
units =
3
Ones
Tens
Tens
Hundreds
Hundreds
1
2
3
Let’sReview
Review
Let’s
Whole Unit (Ones)
Hundredths
Tenths
1 Whole
2Tenths
3 Hundredths
Tenths
Hundredths
1.23
Ones
Let’sReview
Review
Let’s
1
2
3
Let’sReview
Review
Let’s
Multiplication is
repeated addition
5
x3
15
3 + 3 + 3 + 3 + 3 = 15
A Common
Let’s
Review Mistake
Forgetting to take the decimal into
consideration when multiplying.
0.1 x 11 ≠ 11
CoreReview
Lesson
Let’s
0.15 is halfway
7 x 0.1 is 7
between 0.1 and
tenths
0.2
Smart Estimate
7 x 0.15
7
x0.15
=
7
=
7
≈ x0.1 ≈ x0.2
0.7
1.4
Smart estimate:
Between 0.7 and 1.4
Around 1
714x tenths
0.2 is is
14
written
tenths1.4
Hundredths
This is a
reasonable
answer since it
is close to my
smart estimate
Tenths
7 x 0.15
Ones
CoreReview
Lesson
Let’s
1
0
5
CoreReview
Lesson
Let’s
A pencil costs $0.28.
How much do 6 pencils cost?
$0.28 is close
to $.25
6
x0.28
=
6
≈ x0.25
$1.50
Smart estimate:
Around $1.50
Hundredths
This is a
reasonable
answer since it
is close to my
smart estimate
Tenths
6 x $0.28
Ones
CoreReview
Lesson
Let’s
1
6
8
In this lesson you have
learned how to multiply
decimals by whole numbers
by using an area model.
Guided
Practice
Let’s
Review
5 x 0.25
Extension
Let’s
ReviewActivities
Explain why the answer is a decimal when
you multiply a whole number by a
decimal.
Extension
Let’s
ReviewActivities
Estimate the answer and then use an
area model to show the multiplication
of 4 x 0.35.
Quick
Quiz
Let’s
Review
Which area model shows 3 x 0.18?
A
B
C
D