Rounding Integers

Objective

To know how to round any integer

Example

Round 49,682 to the nearest hundred

Answer: 49,700

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Explanation

Rounding means to turn an exact answer into an approximate answer. Words that come up in rounding are "about", "estimate", "approximately", "close to", or "around".

Why would we take an exact answer and make it not exact? Often just to make the number look nice. People also round to make a number easier to do math with. Scientists round to show how accurate their measurements are.

When you round, you pick the place value that you care about. For example, when we say "round to the nearest hundred", we're saying that we don't care about anything smaller than hundreds. That means that tens and units will taken out (made zero). Lets look at the example above

Example

Round 49,682 to the nearest hundred.

1.) First, find the hundreds

49,682

Now let's leave off everything bigger than the hundreds

682

2.) Now we need to decide which is the nearest hundred. Since 687 is between 600 and 700, our choices are to:

• round down to 600

  • Round down means we don't change the digit we're rounding to.

  • Every place smaller than that digit becomes 0.

• round up to 700

  • Round up means we add 1 to the digit we're rounding to.

  • Every place smaller than that digit becomes 0.

How do we know whether to round up or round down? You need to figure out which hundred our number is closest to. Look at the place value just smaller than the one we're rounding to. In this question, since we are rounding to the nearest hundred, we need to look at the tens place

682

Then, remember this important rule:

• If that number is smaller than 5 (meaning 0, 1, 2, 3, or 4), round down.

• If that number is 5 or greater (meaning 5, 6, 7 ,8, or 9), round up.

For this example, since 8 is greater than 5, we round up.

700

3.) Bring this rounded part back to the original number

49,672 49,700

Answer: 49,700

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Examples

Example 1

Round 49,682 to the nearest ten.

1.) First, find the tens

49,682

Now let's leave off everything bigger than the tens

82

2.) Now we need to decide which is the nearest ten. Since 82 is between 80 and 90, our choices are to:

• round down to 80

• round up to 90

Since we are rounding to the nearest ten, we need to look at the units place

82

For this example, since 2 is smaller than 5, we round down.

80

3.) Bring this rounded part back to the original number

49,682 49,680

Answer: 49,680

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Example 2

Round 49,682 to the nearest thousand.

1.) First, find the thousands

49,682

9,682

2.) Since 9,682 is between 9,000 and 10,000 our choices are to:

• round down to 9,000

• round up to 10,000

9,682

6 is greater than 5, round up.

10,000

3.) Bring this rounded part back to the original number

49,682 50,000 (Notice that since we rounded to 10 and 10 has 2 digits, we need to carry the 1)

Answer: 50,000

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Example 3

Round 49,682 to the nearest million.

1.) First, find the millions

0,049,682

2.) Since 0,049,682 is between 0 and 1,000,000 our choices are to:

• round down to 0

• round up to 1,000,000

0,049,682

0 is less than 5, round down.

0

3.) Bring this rounded part back to the original number

0,049,682 0,000,000

Answer: 0

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Practice your skills