Learn on PengiSaxon Math, Course 2Chapter 5: Lessons 41-50, Investigation 5

Lesson 42: Repeating Decimals

In this Grade 7 lesson from Saxon Math Course 2, students learn to identify and write repeating decimals using bar notation over the repetend, distinguishing them from terminating decimals. Students practice converting division problems into repeating decimal form, rounding repeating decimals to a specified number of decimal places, and comparing repeating decimals with terminating decimals. The lesson also introduces how calculators handle repeating decimals through truncation or rounding.

Section 1

๐Ÿ“˜ Repeating Decimals

New Concept

Some divisions produce repeating decimals, where one or more digits, called the repetend, repeat in a pattern forever.

One way to indicate that a decimal number has repeating digits is to write the number with a bar over the repetend where it first appears to the right of the decimal point. For example,

4.2333...=4.23โ€พ0.52727...=0.527โ€พ 4.2333... = 4.2\overline{3} \quad 0.52727... = 0.5\overline{27}

Whatโ€™s next

This card introduces the core idea. Soon, we'll dive into worked examples on writing, rounding, and comparing these special decimals.

Section 2

Repetend

Property

The repeating digits of a decimal number are called the repetend. We use a bar over the repetend where it first appears to the right of the decimal point to write it concisely.

Examples

0.08333...=0.083โ€พ0.08333... = 0.08\overline{3}
5.14285714...=5.142857โ€พ5.14285714... = 5.\overline{142857}
454.54545...=454.54โ€พ454.54545... = 454.\overline{54}

Explanation

Think of the bar as a crown for the digits that repeat forever! Itโ€™s a super handy shortcut, showing which numbers go on an infinite journey, so you don't have to write them out endlessly.

Section 3

Rounding Repeating Decimals

Property

To round a repeating decimal, first remove the bar and write out the repeating pattern past the desired place value. Then, you can apply standard rounding rules to the newly expanded number.

Examples

Round 5.316โ€พ5.31\overline{6} to five decimal places: 5.316666...โ†’5.316675.316666... \rightarrow 5.31667
Round 25.405โ€พ25.\overline{405} to five decimal places: 25.405405...โ†’25.4054125.405405... \rightarrow 25.40541
Round 0.8โ€พ0.\overline{8} to the thousandths place: 0.8888...โ†’0.8890.8888... \rightarrow 0.889

Explanation

You can't round a number that's still hiding its true self! First, un-repeat the decimal by writing it out long-form. After you see the full number, you can round it up or down like any other.

Book overview

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Continue this chapter

Chapter 5: Lessons 41-50, Investigation 5

  1. Lesson 1

    Lesson 41: Using Formulas, Distributive Property

  2. Lesson 2Current

    Lesson 42: Repeating Decimals

  3. Lesson 3

    Lesson 43: Converting Decimals to Fractions, Converting Fractions to Decimals, Converting Percents to Decimals

  4. Lesson 4

    Lesson 44: Division Answers

  5. Lesson 5

    Lesson 45: Dividing by a Decimal Number

  6. Lesson 6

    Lesson 46: Rates

  7. Lesson 7

    Lesson 47: Powers of 10

  8. Lesson 8

    Lesson 48: Fraction-Decimal-Percent Equivalents

  9. Lesson 9

    Lesson 49: Adding and Subtracting Mixed Measures

  10. Lesson 10

    Lesson 50: Unit Multipliers and Unit Conversion

  11. Lesson 11

    Investigation 5: Creating Graphs

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

๐Ÿ“˜ Repeating Decimals

New Concept

Some divisions produce repeating decimals, where one or more digits, called the repetend, repeat in a pattern forever.

One way to indicate that a decimal number has repeating digits is to write the number with a bar over the repetend where it first appears to the right of the decimal point. For example,

4.2333...=4.23โ€พ0.52727...=0.527โ€พ 4.2333... = 4.2\overline{3} \quad 0.52727... = 0.5\overline{27}

Whatโ€™s next

This card introduces the core idea. Soon, we'll dive into worked examples on writing, rounding, and comparing these special decimals.

Section 2

Repetend

Property

The repeating digits of a decimal number are called the repetend. We use a bar over the repetend where it first appears to the right of the decimal point to write it concisely.

Examples

0.08333...=0.083โ€พ0.08333... = 0.08\overline{3}
5.14285714...=5.142857โ€พ5.14285714... = 5.\overline{142857}
454.54545...=454.54โ€พ454.54545... = 454.\overline{54}

Explanation

Think of the bar as a crown for the digits that repeat forever! Itโ€™s a super handy shortcut, showing which numbers go on an infinite journey, so you don't have to write them out endlessly.

Section 3

Rounding Repeating Decimals

Property

To round a repeating decimal, first remove the bar and write out the repeating pattern past the desired place value. Then, you can apply standard rounding rules to the newly expanded number.

Examples

Round 5.316โ€พ5.31\overline{6} to five decimal places: 5.316666...โ†’5.316675.316666... \rightarrow 5.31667
Round 25.405โ€พ25.\overline{405} to five decimal places: 25.405405...โ†’25.4054125.405405... \rightarrow 25.40541
Round 0.8โ€พ0.\overline{8} to the thousandths place: 0.8888...โ†’0.8890.8888... \rightarrow 0.889

Explanation

You can't round a number that's still hiding its true self! First, un-repeat the decimal by writing it out long-form. After you see the full number, you can round it up or down like any other.

Book overview

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

Continue this chapter

Chapter 5: Lessons 41-50, Investigation 5

  1. Lesson 1

    Lesson 41: Using Formulas, Distributive Property

  2. Lesson 2Current

    Lesson 42: Repeating Decimals

  3. Lesson 3

    Lesson 43: Converting Decimals to Fractions, Converting Fractions to Decimals, Converting Percents to Decimals

  4. Lesson 4

    Lesson 44: Division Answers

  5. Lesson 5

    Lesson 45: Dividing by a Decimal Number

  6. Lesson 6

    Lesson 46: Rates

  7. Lesson 7

    Lesson 47: Powers of 10

  8. Lesson 8

    Lesson 48: Fraction-Decimal-Percent Equivalents

  9. Lesson 9

    Lesson 49: Adding and Subtracting Mixed Measures

  10. Lesson 10

    Lesson 50: Unit Multipliers and Unit Conversion

  11. Lesson 11

    Investigation 5: Creating Graphs