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Unit 01 · Whole Numbers and DecimalsLesson

Day 006Multiplying Decimals

LearnClassworkAnswer keyPDF packet ↗
Standards 6.NS.B.3
LEARNING TARGET

I can multiply decimals and use an estimate to place the decimal point.

01 · LEARN

Build the idea

Multiply as whole numbers using the standard algorithm. The product has the total number of decimal places in the two factors before trailing zeros are removed. Check its size against an estimate.

WORKED EXAMPLE 1

Use the standard algorithm: 17.7 × 7.6. Show your regrouping or division steps.

134.52

Compute the whole-number product and restore decimal places: 17.7 × 7.6 = 134.52.

WORKED EXAMPLE 2

Use the standard algorithm: 4.28 × 0.77. Show your regrouping or division steps.

3.2956

Compute the whole-number product and restore decimal places: 4.28 × 0.77 = 3.2956.

02 · PRACTICE

Your turn

Work in order. Start with the foundations, then build toward explanation and application.

  1. Use the standard algorithm: 39.7 × 5.2. Show your regrouping or division steps.

  2. Use the standard algorithm: 29.4 × 3.9. Show your regrouping or division steps.

  3. Use the standard algorithm: 68.4 × 1.3. Show your regrouping or division steps.

  4. Use the standard algorithm: 4.86 × 5.2. Show your regrouping or division steps.

  5. Use the standard algorithm: 3.5 × 3.9. Show your regrouping or division steps.

  6. Use the standard algorithm: 8.93 × 2.1. Show your regrouping or division steps.

  7. Use the standard algorithm: 2.54 × 0.26. Show your regrouping or division steps.

  8. Use the standard algorithm: 7.49 × 0.21. Show your regrouping or division steps.

  9. Ribbon costs $7.16 per meter. What is the exact cost of 0.51 meters? Do not round.

  10. Ribbon costs $1.42 per meter. What is the exact cost of 0.5 meters? Do not round.

03 · CHECK

Answers and reasoning

Reveal the teacher answer key
  1. 206.44

    Compute the whole-number product and restore decimal places: 39.7 × 5.2 = 206.44.

  2. 114.66

    Compute the whole-number product and restore decimal places: 29.4 × 3.9 = 114.66.

  3. 88.92

    Compute the whole-number product and restore decimal places: 68.4 × 1.3 = 88.92.

  4. 25.272

    Compute the whole-number product and restore decimal places: 4.86 × 5.2 = 25.272.

  5. 13.65

    Compute the whole-number product and restore decimal places: 3.5 × 3.9 = 13.65.

  6. 18.753

    Compute the whole-number product and restore decimal places: 8.93 × 2.1 = 18.753.

  7. 0.6604

    Compute the whole-number product and restore decimal places: 2.54 × 0.26 = 0.6604.

  8. 1.5729

    Compute the whole-number product and restore decimal places: 7.49 × 0.21 = 1.5729.

  9. 3.6516 dollars

    Compute the whole-number product and restore decimal places: 7.16 × 0.51 = 3.6516.

  10. 0.71 dollars

    Compute the whole-number product and restore decimal places: 1.42 × 0.5 = 0.71.

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