Learn on PengiEureka Math, Grade 5Chapter 21: Multiplication of a Whole Number by a Fraction

Lesson 4: Find a fraction of a measurement, and solve word problems.

In this Grade 5 Eureka Math lesson from Chapter 21, students learn how to find a fraction of a measurement by converting between units such as pounds and ounces, pints and cups, and yards and feet. Students practice multiplying a fraction by a whole number to express fractional parts of larger units as smaller units, then apply this skill to multi-step word problems. The lesson builds fluency with unit conversions and fraction multiplication using tape diagrams and simplifying strategies.

Section 1

Rewrite a Fraction of a Measurement as Multiplication

Property

To find a fraction of a measurement, rewrite the problem as the fraction multiplied by the equivalent value in a smaller unit.

ab of 1 Large Unitab×(number of smaller units)\frac{a}{b} \text{ of } 1 \text{ Large Unit} \rightarrow \frac{a}{b} \times (\text{number of smaller units})

Examples

Section 2

Solve Word Problems Involving a Fraction of a Measurement

Property

To find a fractional part of a measurement in a word problem, translate the problem into a multiplication expression.
This involves multiplying the fraction by the total measurement, after converting the measurement into a smaller, more manageable unit.

Examples

Book overview

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Chapter 21: Multiplication of a Whole Number by a Fraction

  1. Lesson 1

    Lesson 1: Relate fractions as division to fraction of a set.

  2. Lesson 2

    Lesson 2: Multiply any whole number by a fraction using tape diagrams.

  3. Lesson 3

    Lesson 3: Relate a fraction of a set to the repeated addition interpretation of fraction multiplication.

  4. Lesson 4Current

    Lesson 4: Find a fraction of a measurement, and solve word problems.

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

Rewrite a Fraction of a Measurement as Multiplication

Property

To find a fraction of a measurement, rewrite the problem as the fraction multiplied by the equivalent value in a smaller unit.

ab of 1 Large Unitab×(number of smaller units)\frac{a}{b} \text{ of } 1 \text{ Large Unit} \rightarrow \frac{a}{b} \times (\text{number of smaller units})

Examples

Section 2

Solve Word Problems Involving a Fraction of a Measurement

Property

To find a fractional part of a measurement in a word problem, translate the problem into a multiplication expression.
This involves multiplying the fraction by the total measurement, after converting the measurement into a smaller, more manageable unit.

Examples

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 21: Multiplication of a Whole Number by a Fraction

  1. Lesson 1

    Lesson 1: Relate fractions as division to fraction of a set.

  2. Lesson 2

    Lesson 2: Multiply any whole number by a fraction using tape diagrams.

  3. Lesson 3

    Lesson 3: Relate a fraction of a set to the repeated addition interpretation of fraction multiplication.

  4. Lesson 4Current

    Lesson 4: Find a fraction of a measurement, and solve word problems.