DECIMALS

1
DECIMALS

• Objectives
• Read, write, and compare rational numbers
• Add, subtract, multiply, and divide rational
  numbers (integers decimals)
• Compare and order decimal numbers and integers

2
DECIMALS

• Objectives
• Analyze word problems
• Solve real life problems involving decimals and
  integers

3
DECIMALS

• Activities
• Independent Work
• Pair Work
• Small Group Activities
• Puzzles Games

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DAY 4

• Comparing and Ordering Decimals

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Ordering decimals

• Can you arrange the following prices from
  cheapest to the most expensive?

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McDonalds Menu.Im Lovin It!!

• Double Cheeseburger 0.99
• Big Mac Value Meal 4.79
• Chicken McNuggetts Meal 3.80
• Small Drink 0.99
• McFlurry 1.97
• Salad 4.80
• 2 Cheeseburger Meal 3.70
• Ice Cream Cone 0.87

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Order Up!Least Expensive to Most Expensive

• Ice Cream Cone .87
• Double Cheeseburger .99
• Small Soft Drink .99
• McFlurry 1.97
• 2 Cheeseburger Meal 3.70
• Chicken McNuggetts Meal 3.80
• Big Mac Value Meal 4.79
• Chicken Salad 4.80

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What Does It Mean to Compare Decimals?

• When we compare we use terms such as
• Less than lt
• Greater than gt
• Equal to
• Comparing decimals is similar to comparing whole
  numbers.
• 45 lt 47 45 is less than 47
• 150 gt 105

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Place Value
1,000 100 10 1 0.1 0.01 0.001 0.0001

Hundreds
Ones
Thousands
Tens
Tenths
Hundredths
Thousandths
Ten-thousandths
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Half pipe Scores Who scored the highest?

• Check at the numbers on the left of the decimal
  point. These are the whole numbers. Which one is
  the greatest?
• If there are more than two of these numbers,
  check the decimal places.
• In this case, it is obvious that Jacob scored the
  highest, the score being 46.1.
• Then we have Sara, Danny and Ross at 42.
• 42.1
• 42.5
• 42.0
• Compare the number after the decimal point and
  order from least to greatest

Sara 42.1
Danny 42.5
Ross 42.0
Bethany 40.7
Jacob 46.1
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Lets Try Using A Number Line
NAMES Sara POINTS 42.1
Danny 42.5
Ross 42.0
Bethany 40.7
Jacob 46.1
42
40.7
46.1
42.1
42.0
42.5
Since numbers to the right are greater than
numbers, then we can say that the winner is
Jacob (46.1), Danny (42.5), Sarah (42.1), Ross
(42.0) and Bethany (40.7)
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Equivalent Decimals

• Decimals that name the same number are called
  equivalent decimals.
• 0.60 and 0.6
• Are these the same???

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0.60
0.6












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Annexing Zeros

• This means placing a zero to the right of the
  last digit in a decimal.
• 0.6 0.60
• Although we added a zero, the value of the
  decimal did not change!!
• Annexing or adding zeros is useful when ordering
  a group of decimals.

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Ordering Decimals

• We can order decimals from least to greatest or
  we can order from greatest to least.
• Lets try an example
• Order 15, 14.95, 15.8, and 15.01 from least to
  greatest

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15, 14.95, 15.8, 15.01

• LEAST TO GREATEST
• First, line up the decimal points
• 15
• 14.95
• 15.8
• 15.01

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15, 14.95, 15.8, 15.01

• Next, annex zeros so that each number has the
  same number of decimal places
• 15.00
• 14.95
• 15.80
• 15.01

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15, 14.95, 15.8, 15.01

• Finally, use place value to compare the decimals.
  Always start from the left!!
• 15.00
• 14.95
• 15.80
• 15.01
• 14.95, 15, 15.01, 15.8

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One More Example

• Order these numbers from greatest to least
• 35.06, 35.7, 35.5, 35.849
• Did you write-
• 35.849
• 35.700
• 35.500
• 35.060

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TEAMMATES CONSULT

• Answer the following
• Arrange the numbers from greatest to least
• 0.808, 0.080, 0.80, 0.888

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Teammates Consult

• Answer the following
• The five car racers obtained the following time
  Who reached the finish line 1st, 2nd, 3rd, 4th
  and last?
• BMW 4.2
• Corvette 4.16
• Ferrari 4.25
• Porche 4.03
• Mercedes 4.22

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Teammates Consult

• Answer the following
• The preschool children took care of some rabbits
  in their classroom. They fed each one daily. At
  the end of two weeks, the six rabbits weighed
  7.15 7.02 7.25 7 7.05 7.02.
• Arrange the weights in order from least to
  greatest.

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Optional

• http//www.mathsisfun.com/numbers/decimals-dividin
  g-animation.html

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Day 6

• Multiplication of
• Decimals

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Multiplication of Decimals

• Remember
• Multiplication is REPEATED ADDITION
• So, if you have 4 x 3.5, this means-
• 3.5 3.5 3.5 3.5

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Multiplication of Decimals

• 3.5 3.5 3.5 3.5 can be written as

3.5 3.5 3.5 3.5
14.0
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Multiplication of Decimals

• Try these!
• 1.2 x 6
• 5 x 3.2

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Multiplication of Decimals

• Did you re-write the problems vertically?
• 1.2
• x 6
• 7.2

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Multiplication of Decimals

• 5 x 3.2
• 3.2
• X 5
• 16.0

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Multiplication of Decimals

• What should be done when both factors have
  decimal numbers?
• Example 3.2 x 1.4

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Multiplication of Decimals

• 3.2 x 0.4
• Re-write the equation
• 3.2
• X 0.4

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• 3.2
• X 0.4

• Multiply the digits as if they were whole numbers

• Look at the problem and count the digits after
  the decimal point. 3.2 x 0.4

12 8

12 0
3.2 x 0.4
24 8
2.48
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Try These!
0.31 x 0.11 .17 x .10
1.23 x 2.1 2.21 x 31.2