Post on 07-Jan-2016
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Kristina has 4.5 pounds of taffy. She wants to share it evenly among
10 people. How much taffy will each person receive?
In this lesson you will learn how to divide decimal
numbers by powers of 10 by using what you know about
place value.
Let’s Review
30.0 6.0 0.1 0.02
+ 0.005
36.
Ones Period DecimalThousandths
Period
Hundreds
Tens Ones
Tenths
Hundredths
Thousandths
3 6 1 2 5 125
Let’s Review
15.6 ÷ 3 = 5.2
dividendquotient
divisor
Let’s Review
20.6 ÷ 10
(20 + 0.6) ÷ 10
2 0.06 2.06
+
=
(20 ÷ 10) (0.6 ÷ 10)
+
A Common Misunderstanding
Not thinking about the place value of the digits when dividing.
60.4 ÷ 100
(60 ÷ 100) + (4 ÷ 100)
(60 ÷ 100) + (0.4 ÷ 100) = 0.604
= 0.64
Let’s Review
101 =
102 =
103 =
104 =
105 =
1 x 1010
10 x 10100
10 x 10 x 101,000
10 x 10 x 10 x 1010,000
10 x 10 x 10 x 10 x 10100,000
The value of the exponent tells us how many times ten is multiplied by itself.
We can also say that the number of zeros in the product is equal to the value of the exponent.
Powers of 10
Core Lesson
= 1.0 = 0.1 = 0.01
Core Lesson
Ones Tenths Hundredths
1.3 ÷ 10
(1.0 ÷ 10) (0.3 ÷ 10)+
= 0.13
= 0.1 = 0.03
Core Lesson
Ones PeriodThousandths
Period
Hundreds
Tens Ones
Tenths
Hundredths
Thousandths
1.3 ÷ 11.3 ÷ 10
1.3 ÷ 100
1 . 3
Do you notice any patterns in the
dividends and the quotients?
Each time you divide a decimal by a power of 10, the digits in the quotient shift to the right.
.
.
1 . 3 1 3 1 . 3 1 3 0 1 3
Core Lesson
1.3 ÷ 1 = 1.3
1.3 ÷ 101
1.3 ÷ 102
But what is happening to the
location of the decimal point?
= 0.13
= 0.013
Each time you divide a decimal by a power of 10, the decimal point shifts to the left the same number of places as the value of the exponent.
1
2
Core Lesson
4.5 ÷ 10
This makes sense because 0.45 is 10 times smaller than
4.5
I can move the decimal point one place to the left in
4.5
4.5 = 0.45
In this lesson you have learned how to divide decimal numbers by powers of 10 by using what you know about place value.