1. The decimal point helps us to keep track of where the "ones" place is.
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In our number system, digits can be placed to the left and right of a decimal point, to indicate numbers greater than one or less than one.
1.0 or 0.1
The decimal point helps us to keep track of where the "ones" place is.
It's placed just to the right of the ones place.
As we move right from the decimal point, each number place is divided by 10. 1

2. Parts of the number
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The whole number portion of a decimal number are those digits to the left of the decimal place.
Example:
In the number 23.65, the whole number portion is 23.
In the number 0.024, the whole number portion is 0.
What are the decimal portions of these numbers? 2

3. 4/17/2017 3

4. 4/17/2017 4

5. Five hundred forty-eight thousandths 0.548
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Hint #1: Remember to read the decimal point as "and" -- notice in the last two problems what a difference that makes!
Five hundred and forty-eight thousandths
Hint #2: When writing a decimal number that is less than 1, a zero is normally used in the ones place:
Five hundred forty-eight thousandths 0.548
0.548 not .548 5

6. Expanded Form of a Decimal Number
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Expanded Form of a Decimal Number
Expanded Form of a Decimal Number
The expanded form of a decimal number is the number written as the sum of its whole number and decimal place values.
Example:
3 + 0.7 + 0.06 +  =
100 + 3 + 0.06 = 6

7. Just a Note… BUT The number 14.504 is equal to 14.504000
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Just a Note…
The number is equal to
Adding extra zeros to the right of a decimal number does not change its value
BUT
The number 14,505 ≠14,504,000 7

8. 4/17/2017
Adding Decimals =
8.4
+ 1.22
9.62
12.924 + 3.6 =
12.924
+3.600
16.524
ALWAYS be sure to stack the numbers so the decimals stay above one another!!! 8

9. Subtracting Decimals 10.66 – 5.22 = 10.66 -5.22 5.44
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Subtracting Decimals
10.66 – 5.22 =
10.66
-5.22
5.44
= Add extra 0's, using the fact that 18.2 = 9

10. 4/17/2017
Multiplying Decimals
If not using a calculator, count the number of decimal places in all terms to be multiplied
The answer should contain that many decimal places.
5.222 m
x m
m2 (5 decimal places) 10

11. Dividing with Decimals
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Dividing with Decimals 11

12. Dividing Decimals Dividend ÷ divisor = quotient divisor )dividend
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Dividing Decimals
Dividend ÷ divisor = quotient
divisor )dividend
÷ 4.76 = 23.4 12