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Think About It!

Goal: Round large numbers using benchmark numbers.

Elijah and his mom have 132 apples. They want to round 132 to the nearest ten. We will use benchmark numbers to round. Benchmark numbers are the closest whole tens on a number line. Whole tens are numbers that end in 0.

We know 132 is between 100 and 200. Let’s use 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200 as our benchmark numbers.

132 is between 130 and 140 on this number line. Click to see 132 closer.

Is 132 closer to 130 or 140?

That’s right! 132 is closer to 130. 132 rounds down to 130. That means Elijah and his mom have about 130 pieces of fruit!

Let's try it again. How can we round the number 267?

Step 1 Step 2 Step 3

We need benchmark numbers! 267 is between 200 and 300. What will our benchmark numbers be?

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200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300

Here is a number line with our benchmark numbers. We need to choose the two benchmark numbers closest to 267.

267 is between which two numbers?

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267 is between 260 and 270.

Here is 267 on our number line.

Is 267 closer to 260 or 270?

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267 is closer to 270. 267 rounds up to 270. 267 is about 270.