Round Numbers

Grade 4: Unit 4: Lesson 16

Let’s round some large numbers.

Number Talk: Missing Numbers

Warm-Up

Find the value that makes each equation true mentally.

Let’s Talk About It!

What do all four equations have in common?

Is 500 the nearest multiple of 100 for 421? How do you know?

Is 7,000 the nearest multiple of 1,000 for 6,421?

Is 10,000 the nearest multiple of 10,000 for 6,421?

Round to What?

Activity 1

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Noah says that 489,231 can be rounded to 500,000.

Priya says that it can be rounded to 490,000.

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a. Explain or show why both Noah and Priya are correct. Use a number line if it helps.

b. Describe all the numbers that round to 500,000 when rounded to the nearest hundred- thousand.

c. Describe all the numbers that round to 490,000 when rounded to the nearest ten-thousand.

d. Name two other numbers that can also be rounded to both 500,000 and 490,000.

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Let’s Talk About It!

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How did you find numbers that can be rounded to both 500,000 and 490,000?

Some Numbers to Round

Activity 2

• MLR8: Discussion Supports

Your teacher will show you six numbers. Choose at least three numbers and round each to the nearest 100,000, 10,000, 1,000, and 100.

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Record your work in the table. Use a number line if it is helpful.

Let’s Talk About It!

Share your responses to complete the table

Rounded Populations

Activity 3

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What do you notice? What do you wonder?

The table shows the estimated populations of two cities in the United States, based on surveys in 2018.

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Here are three other cities and their estimated populations:

• Charlotte, NC: 872,498

• Jacksonville, FL: 903,889

• Virginia Beach, VA: 450,189

Match the populations of Charlotte, Jacksonville, and Virginia Beach to the rounded numbers in the table. Then, complete the table.

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The table shows three ways of rounding large numbers.

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a. To get a rough idea of how many people are in these cities, which ways of rounding seem appropriate?

b. To compare the populations or put them in order by size, which ways of rounding are more helpful? Less helpful?

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Let’s Talk About It!

Lesson Synthesis

What do you notice? What do you wonder?

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Why does 370,130 round to the same number when rounded to the nearest 10,000 and 1,000?

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Why does 4,896 round to 0?

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Why does 985,411 round to 1,000,000 instead of a six-digit number in the hundred-thousands?

Round Three Ways

Cool-Down

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Round 569,003 to the nearest 100,000, 10,000 and 1,000. Explain or show your reasoning.

Cool-Down: Round Three Ways

Image Citations

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