Our objective today is to review Adding and Subtracting Fractions. - PowerPoint PPT Presentation

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Our objective today is to review Adding and Subtracting Fractions.

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When I think of fractions, I always think of Pizza. Pizza will be our theme today! – PowerPoint PPT presentation

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Title: Our objective today is to review Adding and Subtracting Fractions.


1
Our objective today is to review Adding and
Subtracting Fractions.
  • When I think of fractions, I always think of
    Pizza. Pizza will be our theme today!

2
Some Warm Ups
  • Write the following as fractions.
  • (1) 2 out of 5 slices have mushroom.
  • (2) Circles that are colored green.
  • (3) Circles that are not colored.
  • (4) There are 3 pies. 2 pies and three out
    of eight slices
  • of a third pie have anchovies.

3
Estimating Sums and Differences
  • A benchmark is a number used to replace fractions
    that are less than 1.
  • We use a benchmark of 0, ½, and 1 when estimating
    sums and differences of fractions.

Description Examples Benchmark
Numerator is very small when compared to denominator 1/8, 3/16, 2/25, 9/100 0
Numerator is about one half of the denominator 3/8,9/16,11/25,52/100 1/2
Numerator and denominator are close to each other 7/8,14/16,23/25,95/100 1
4
  • Choose a benchmark for the measurement inch
  • 7 is half of 16
  • ½ inch is the benchmark
  • Choose a benchmark for inch
  • 1 inch is the benchmark

5
  • Estimate

6
  • Estimate
  • Estimate each sum or difference
  • (1) ½ (2)
    2

7
Adding and Subtracting with Like denominators
  • To add or subtract fractions with like
    denominators, add (subtract) the numerators and
    keep the same denominator.
  • Find

8
  • (1) At a pizza place, 4/12 of a pepperoni pie and
    7/12 of a vegetable pie were sold. How much more
    vegetable pies than vegetable pies were sold?
    3/12
  • Which solution to is correct?
    Explain your reasoning.
  • The first equation is correct.


9
Adding and Subtracting with Unlike denominators
  • Write the fraction using a common denominator
  • Perform the operation in the numerator.
  • Denominators remain the same.

10
Your Turn
  • The famous sauce recipe calls for ¼ cup of pepper
    and cups of oregano. How much more oregano
    than pepper is needed?
  • Find 5/6
  • Find 1/3

11
Mixed Numbers
  • When you say I ate a slice and a half of pizza,
    or I have a pizza party to attend at quarter pass
    five, you are using mixed numbers.
  • Mixed number is a whole number and a fraction
  • Write as a mixed number
  • ? 6
  • Write as a mixed number. 1 ½

12
Adding Mixed Numbers
  • You can find the sum of mixed numbers by adding
    the whole number and fractions parts separately.
    Then you combine the two parts to find the total.
  • Add 8½ 6 ¼
  • 8 ? 8 ? LCD is 4. Write fractions
    with same denominator.
  • 6 ? 6
  • ____________
  • 14 ? Add whole numbers, and then
    fractions.

13
  • Lets take a break!
  • How about a puzzle?
  • Click here for puzzle!

14
Your Turn
  1. The depth of a pizza pan is 2 ½ cm deep. After
    baking the pizza rises 1 ¾ cm above the pan. How
    deep is the pizza? Remember to convert improper
    fractions to mixed number. 4 ¼ cm

15
Subtracting Mixed Numbers
  • When you subtract mixed numbers, you need to
    write the fractions with a common denominator.
    Then you can subtract the whole numbers and the
    fractions separately.
  • Fresh vegetables are grown for toppings. Zesty
    tomatoes are taken from a plant that is 11 ¾
    inches tall. A mushroom plant is 7 5/8 inches
    tall. What is the difference between the heights
    of the plants.
  • 4 1/8inches

16
Renaming a Whole Number
  • Find 7 2
  • How would you convert 7 to a mixed number?
    Remember to use 8 as the denominator in this
    case!
  • 7 ? 6 ? Rename 7 as 6 1 6
  • - 2 ? - 2 ? Subtract the whole
    numbers. Then subtract the _____________
    fractions.
  • 4

17
Your Turn
  • Giorgio made 10 pepperoni pies for lunch. He
    sold 7 ¼ pies. How many pies were left over from
    lunch? 2 ¾ pies
  • Find 5 3 1 1/3


18
Renaming a Mixed Number
  • Find 9 - 1
  • Here we face a problem. Using the LCD 8, the top
    numerator is smaller than the bottom numerator.
  • ? 9 ? 8 Rename 9 as 8 1 or 8
  • -1 ? -1 ? -1
  • _________________
  • 7

19
Your Turn
  • The vegetable man delivers 7 pounds of fresh,
    red, ripe tomatoes on Wednesday. 5 ¾ pounds of
    tomatoes were delivered on Tuesday. How much more
    tomatoes were delivered on Wednesday than
    Tuesday? 1 5/12

20
  • The benchmark for 4/5 is ______. 1
  • Using benchmarks 0, ½ and 1 estimate the sum of
    1 ½
  • Find each sum or difference
  • (a) 1/2 (b) 3/5
  • Mario the delivery boy rode his bike miles to
    deliver his first order. His second order was
    miles. What was the total distance Mario rode
    his bike? 13/15 miles

21
  • Out of 6 pizza pies, 2 did not have any
    toppings. How many pizza pies had toppings.
    3 3/5pies
  • 25 - 8 16 7/9

22
Dont forget the dessert
  • 8. Tonys pizzeria is famous for its desserts.
    The following is the ingredients for its mouth
    watering recipe for its Chocolate Chip Cookie
    Pizza. This recipe serves 12.
  • How much chocolate chips would be needed to serve
    24 people? 2 2/7
  • How much more chocolate chip dough is needed than
    caramel topping? 11/12
  • What is the total amount of chocolate chip and
    pecan needed? 2 9/14

Ingredients 2 2/3 cup refrigerated chocolate
chip cookie dough 1 1/7 cup chocolate chips 1 1/2
cup pecans -- chopped 1 ¾ cup caramel ice cream
topping This recipe for Chocolate Chip Cookie
Pizza serves/makes 12
23
Congratulations, you really do understand all
about fractions!
  • You did a wonderful jobTreat yourself to some
    PIZZA!!
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