Lesson 8 Round Decimals

    • Let’s round decimals to the nearest whole, tenth, and hundredth.

Warm-up Estimation Exploration: Number Line

What number might be represented on the number line?

Number line. 2 evenly spaced tick marks. First tick mark, 0. Last tick mark, 1. Point left of halfway between tick marks.

Record an estimate that is:

too low

about right

too high

Activity 1 Name that Number

Problem 1

Jada locates 15.53 on the number line. Do you think Jada accurately located the number?

Number line.

Problem 2

A number is located between two tick marks on each number line. Label those tick marks and then estimate the number.

  1. Number line.
  2. Number line.
  3. Number line.

Activity 2 Which Number is Closest?

  1. Round 6.273 to the nearest whole number, tenth, and hundredth. Use the number lines if they are helpful. Explain or show your reasoning.

    Number line. 11 evenly spaced tick marks. First tick mark, 6. Last tick mark, 7.
    Number line. 11 evenly spaced tick marks. First tick mark, 6 and 2 tenths. Last tick mark, 6 and 3 tenths.
    Number line. 11 evenly spaced tick marks. First tick mark, 6 and 27 hundredths. Last tick mark, 6 and 28 hundredths.

  2. Round 4.158 to the nearest whole number, tenth, and hundredth.

Activity 3 Round the Numbers

Round each number to the nearest whole number, tenth, and hundredth.

nearest whole number

nearest tenth

nearest hundredth

34.482

99.909

5.555

19.509

Practice Problem

Problem 1

  1. What is 0.374 rounded to the nearest hundredth? Explain or show your reasoning. Use the number line if it’s helpful.

  2. What is 9.893 rounded to the nearest tenth? What about to the nearest hundredth? Draw a number line if it is helpful.