Decimals

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# Decimals - PowerPoint PPT Presentation

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. Decimals. The decimal point helps us to keep track of where the &quot;ones&quot; place is. . OR. It's placed just to the right of the ones place. .

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## PowerPoint Slideshow about 'Decimals' - mulan

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Presentation Transcript
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

Decimals

OR

• It's placed just to the right of the ones place.
Parts of the number

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?

As we move right from the decimal point, each number place is divided by 10.

• As we move to the left from the decimal point, each number is multiplied by 10.
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 + 0.002 = 3.762

100 + 3 + 0.06 = 103.06

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 500.048

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 thousandths0.548

Just a Note…

The number 14.504 is equal to 14.504000

Adding extra zeros to the right of a decimal number does not change its value

BUT

The number 14,505 ≠14,504,000

8.4 + 1.22 =

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!!!

Subtracting Decimals

10.66 – 5.22 =

10.66

-5.22

5.44

18.2 - 6.008 =

Add extra 0's, using the fact that 18.2 = 18.200

18.200

- 6.008

12.192

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 ft

x 4.11 ft

21.46242 ft2 (5 decimal places)