How do you multiply 7 x 0.15?
Jan 19, 2016
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’s ReviewLet’s Review
Hundreds
Tens Ones
2 groups of ten = 20
3 single units = 3
1 group of 100 = 100
Ones
Hundreds Tens Ones
1 2 3
Let’s ReviewLet’s Review
Whole Unit (Ones)
Tenths
Hundredths
Let’s ReviewLet’s Review
Tenths Hundredths
Ones Tenths
Hundredths
1 2 3
1.23
1 Whole 2 3
Let’s ReviewLet’s Review
Multiplication is repeated addition
5 x315
3 + 3 + 3 + 3 + 3 = 15
Let’s ReviewA Common Mistake
Forgetting to take the decimal into consideration when multiplying.
0.1 x 11 ≠ 11
Let’s ReviewCore Lesson Smart Estimate7 x 0.15
7 x 0.1 is 7 tenths
7 x 0.2 is 14 tenths
14 tenths iswritten 1.4
Smart estimate:
Between 0.7 and 1.4Around 1
0.15 is halfway between 0.1 and
0.2
0.7 1.4
7
x0.15
= 7
≈ x0.1
= 7
≈ x0.2
Let’s ReviewCore Lesson 7 x 0.15
Ones Tenths
Hundredths
1 0 5
This is a reasonable
answer since it is close to my
smart estimate
Let’s ReviewCore LessonA pencil costs $0.28.
How much do 6 pencils cost?
$0.28 is close to $.25
Smart estimate: Around $1.50
$1.50
6
x0.28
= 6
≈ x0.25
Let’s ReviewCore Lesson 6 x $0.28
Ones Tenths
Hundredths
1 6 8
This is a reasonable
answer since it is close to my
smart estimate
In this lesson you have learned how to multiply decimals by whole numbers by using an
area model.
Let’s ReviewGuided Practice
5 x 0.25
Let’s ReviewExtension Activities
Explain why the answer is a decimal when you multiply a whole number by a decimal.
Let’s ReviewExtension Activities
Estimate the answer and then use an area model to show the multiplication of 4 x 0.35.
Let’s ReviewQuick Quiz
Which area model shows 3 x 0.18?
A B C D