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Fractions as a Multiple of Unit Fractions

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Fractions as a Multiple of Unit Fractions
CCSS.MATH.CONTENT.4.NF.B.4.A

Basics on the topic Fractions as a Multiple of Unit Fractions

Content

In this Video

Axel and Tank are out to dinner at their favorite pizza place. They need to figure out which pizza has enough slices to make a whole pizza for them to share. They will use multiples of unit fractions to determine the amount of pizza. We will learn what is a unit fraction 4th grade and how to make multiples of unit fraction

What is a Unit Fraction?

A unit fraction is one part of a whole that is divided into equal parts. A unit fraction has 1 as the top number, which is the numerator.

What is a Unit Fraction Example?

⅙ is a unit fraction.

What is a Multiple of a Unit Fraction?

Multiples of unit fractions are fractions created by multiplying the fraction by whole numbers. Here are some examples:

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Follow-Up Activities for Fractions as Multiples of Unit Fractions

After the video there is continued practice with learning ‘ What is a unit fraction in math?’ and ‘What is a multiple of a unit fraction?’ with multiples of unit fractions worksheets.

Transcript Fractions as a Multiple of Unit Fractions

Axel and Tank are out to dinner at their favorite pizza place. They need to figure out which pizza has enough slices to make a whole pizza for them to share. We can help Axel and Tank determine how much of each pizza there is by calculating "Multiples of a Unit Fraction". A unit fraction is a fraction that has one in the numerator and a whole number in the denominator. One-sixth is an example of a unit fraction. The whole is divided into six equal parts... and each part has a value of one-sixth. We can use repeated addition to find multiples of unit fractions... or look at them as multiples on a number line. We can also solve for the multiple of a unit fraction by setting up a multiplication equation. Let’s look at the anchovy pizzas in the case. The anchovy pizzas are divided into thirds… and each slice has a value of one-third. Now, look at the number of pizza slices. There are TWO, "one-third slices". We can write this as a multiplication equation to calculate the total amount of anchovy pizza available. First, write the number of unit fractions being grouped. There are two. Next, write the unit fraction that is represented. The unit fraction is one-third. We are going to multiply two times one-third. First, let's look at the denominator. The whole is STILL divided into thirds, so the denominator in the answer doesn’t change. Now, multiply the whole number and the numerator … two times one is two. The anchovy pizza has two-thirds of a pizza available... which is not enough for Axel and Tank to share a whole pizza. [Disappointed let's out a big sigh] "Sigh!" Next let's calculate how much of the Veggie Delight pizza is available. First, look at the number of unit fractions being grouped... and the unit fraction. How many slices, or unit fractions, of pizza, are being grouped? (...) There are four. What is the unit fraction for the veggie pizza? (...) Since there are five parts or slices, in a whole pizza the unit fraction is one-fifth. The next step is to write a multiplication equation. What are we multiplying? (...) Four times one-fifth. When we multiply, the denominator remains the same because the pizza is still sliced in fifths. Multiply the whole number with the numerator... four times one is four. There are four-fifths of a Veggie Delight pizza in the case... which is STILL not enough to make a whole pizza to share. Finally, let's calculate how much of the Under the Sea Supreme pizza is available. What is the first step? (...) Count how many unit fractions there are. (...) There are six. What is the second step? (...) Determine the unit fraction for the number of parts the whole pizza is divided into. What is the unit fraction for the Under the Sea Supreme? (...) The unit fraction is one-fourth. What is the next step? (...) Set up the multiplication equation. What are we multiplying? (...) Six times one-fourth. How much of the pizza is in the case? (...) There are six-fourths of Under the Sea Supreme pizza. Six-fourths or one and one half. There is more than enough for the very hungry Axel and Tank to order a whole pizza! Remember,(...) we can find the multiples of a unit fraction through multiplication. First, find the number of unit fractions being grouped together… and then, write the unit fraction being represented. Multiply the whole number and the unit fraction. When multiplying, start with the denominator. The denominator doesn't change. Finally, multiply the whole number with the numerator. [Excited to eat his pizza!] “Mmmmm,(...) Under the Sea Supreme!” “My FAVORITE!!!” [Just as Tank is about to take a bite, all of the toppings swim off of his pizza! His face looks shocked!]

Fractions as a Multiple of Unit Fractions exercise

Would you like to apply the knowledge you’ve learned? You can review and practice it with the tasks for the video Fractions as a Multiple of Unit Fractions .
  • Help Axel and Tank to choose a whole pizza.

    Hints

    If, when added, the numerator and denominator are the same, this is equivalent to a whole. $\frac2 6$ + $\frac4 6$ = $\frac6 6$ which is 1 whole.

    Count all the slices of pizza. Is this the same as the number of portions it has been cut in to?

    Solution
    • The first pizza has $\frac3 4$ in total. This is NOT equivalent to a whole.
    • The second pizza has $\frac3 3$ in total. This IS equivalent to a whole so is CORRECT.
    • The third pizza has $\frac5 6$ in total. This is NOT equivalent to a whole.
    • The fourth pizza has $\frac8 8$ in total. This IS equivalent to a whole so is CORRECT.
  • Multiplying pizza slices.

    Hints

    Count how many pizza slices there are in total. This is the factor you are multiplying by.

    Count how many parts the pizza has been sliced in to. If it has been sliced into 6, the unit fraction would be $\frac1 6$.

    Solution
    • For the first pair: There are 5 slices in total and each slice is $\mathbf{\frac{1}{4}}$ since the pizzas have been cut into 4 parts.
    • For the second pair: There are 5 slices in total and each slice is $\mathbf{\frac{1}{6}}$ since the pizzas have been cut into 6 parts.
    • For the third pair: There are 5 slices in total and each slice is $\mathbf{\frac{1}{3}}$ since the pizzas have been cut into 3 parts.
    • For the fourth pair: There are 4 slices in total and each slice is $\mathbf{\frac{1}{5}}$ since the pizzas have been cut into 5 parts.
  • Cookie dough dessert.

    Hints

    How many slices do they eat in total?

    Have they eaten more than a whole cookie dough pizza?

    If they have eaten a whole cookie dough pizza plus a bit more, then the answer should be a mixed number.

    Solution

    Axel and Tank eat 7 slices. Each slice is $\mathbf{\frac{1}{6}}$ so we need to find: 7 x $\mathbf{\frac{1}{6}}$.

    Since $\mathbf{\frac{6}{6}}$ is equal to one whole, we know that they have eaten 1 whole pizza PLUS $\mathbf{\frac{1}{6}}$ of a pizza which equals: 1$\mathbf{\frac{1}{6}}$

  • Multiply the unit fractions.

    Hints

    First multiply the factor by the numerator, for example with 5 x $\frac1 3$ solve 5 x 1. Then write this above the denominator. $\frac5 3$.

    Convert the improper fraction into a mixed number, $\frac5 3$ becomes 1 $\frac2 3$.

    Solution
    • Axel and Tank are ordering lots of pizzas for a pizza party. They order 10 x $\mathbf{\frac{1}{3}}$ veggie slices of pizza. In total they have 3 $\mathbf{\frac{1}{3}}$ veggie pizzas.
    • They order 8 x $\mathbf{\frac{1}{5}}$ anchovy slices of pizza. In total they have 1 $\mathbf{\frac{3}{5}}$ anchovy pizzas.
    • Finally, they order 9 x $\mathbf{\frac{1}{4}}$ sea supreme slices of pizza. In total they have 2 $\mathbf{\frac{1}{4}}$ sea supreme pizzas.
  • What is a unit fraction?

    Hints

    Count how many parts the pizza shape has been cut in to. This is the bottom part of your fraction (the denominator).For example, a pizza cut into 5 would have 5 as the denominator.

    Remember that a unit fraction always has 1 as the numerator (top part of the fraction).

    Solution

    This pizza shape has been cut in to three parts so the bottom part of the fraction (denominator) is 3.

    Each slice is 1 out of 3 or $\frac1 3$. A unit fraction always has 1 as the numerator.

  • Ordering fractions.

    Hints

    If the answer can be simplified, reduce it to its simplest form.

    Convert the improper fraction to a mixed number.

    First multiply the factor by the numerator to find the improper fraction.

    Solution

    The order of the totals from smallest to largest are:

    • 10 x $\mathbf{\frac{1}{8}}$ = 1$\frac2 8$ = 1 $\mathbf{\frac{1}{4}}$
    • 6 x $\mathbf{\frac{1}{4}}$ = 1$\frac2 4$ = 1 $\mathbf{\frac{1}{2}}$
    • 14 x $\mathbf{\frac{1}{8}}$ = 1$\frac6 8$ = 1$\mathbf{\frac{3}{4}}$
    • 9 x $\mathbf{\frac{1}{4}}$ = 2$\mathbf{\frac{1}{4}}$
    • 5 x $\mathbf{\frac{1}{2}}$ = 2$\mathbf{\frac{1}{2}}$