Subjects
Grades
Rounding a Number | Elementary
Concept sheet | Mathematics
Grade
1-6
Table of contents
1st and 2nd Grade
Rounding a number means finding the nearest number that ends in one or more zeros.
We can round to the nearest ten or the nearest hundred.
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A number rounded to the nearest ten will end with 1 zero.
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A number rounded to the nearest hundred will end with 2 zeros.
Round the number 236 to the nearest ten and the nearest hundred.
Rounding to the Nearest Ten
We know that the number 236 is between 230 and 240.
Using a number line, we can determine if 236 is closer to 230 or 240.
The number 236 is closer to 240 than 230.
So, when we round 236 to the nearest ten, we get 240.
Rounding to the Nearest Hundred
We know that the number 236 is between 200 and 300.
Using a number line, we can determine if 236 is closer to 200 or 300.
The number 236 is closer to 200 than 300.
So, when we round 236 to the nearest hundred, we get 200.
Answers:
|
Number to round |
Number rounded |
Number rounded |
|---|---|---|
|
236 |
240 |
200 |
When a number is exactly halfway between 2 numbers, we always round it up to the higher number.
For example, let’s say we want to round 25 to the nearest ten. Even though 25 is as close to 20 as it is to 30, we have to round it up to 30.
Another example: We want to round 350 to the nearest hundred. Even though 350 is as close to 300 as it is to 400, we have to round it up to 400.
3rd and 4th Grade
Rounding a number means finding the nearest number that ends in one or more zeros.
A natural number can be rounded up or down to any place value.
For example, we can round to the hundreds place or the tens place. All the digits to the right of the rounded digit will become zeros.
Round the number 236 to the nearest ten and the nearest hundred.
Rounding to the Nearest Ten
We know that the number 236 is between 230 and 240.
Using a number line, we can determine if 236 is closer to 230 or 240.
The number 236 is closer to 240 than 230.
So, when we round 236 to the nearest ten, we get 240.
Rounding to the Nearest Hundred
We know that the number 236 is between 200 and 300.
Using a number line, we can determine if 236 is closer to 200 or 300.
The number 236 is closer to 200 than 300.
So, when we round 236 to the nearest hundred, we get 200.
Answers:
|
Number to round |
Number rounded |
Number rounded |
|---|---|---|
|
236 |
240 |
200 |
We can also round a decimal number to any place value. For example, we could round to the ones place or the tenths place. In this case, all the digits to the right of the rounded digit would become zeros.
Round 37.82 to the nearest unit and the nearest tenth.
Rounding to the Nearest Unit
We know that 37.82 is between 37 and 38.
Using a number line, we can determine if 37.82 is closer to 37 or 38.
The number 37.82 is closer to 38 than 37.
So, when we round 37.82 to the nearest unit, we get 38.
Rounding to the Nearest Tenth
We know that 37.82 is between 37.8 and 37.9.
Using a number line, we can determine if 37.82 is closer to 37.8 or 37.9.
The number 37.82 is closer to 37.8 than 37.9,
So, when we round 37.82 to the nearest tenth, we get 37.8.
Answers:
|
Number to round |
Number rounded |
Number rounded |
|---|---|---|
|
37.82 |
38 |
37.8 |
When a number is exactly halfway between 2 numbers, we always round it up to the higher number.
For example, let’s say we want to round 25 to the nearest ten. Even though 25 is as close to 20 as it is to 30, we have to round it up to 30.
Another example: We want to round 98.50 to the nearest unit. Even though 98.50 is as close to 98 as it is to 99, we have to round it up to 99.
Instead of using a number line to see which number the digit we’re rounding is closer to, we can use the following strategy.
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Find the digit in the position you’re rounding to.
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Look at the digit directly to the right.
If it’s 0, 1, 2, 3, or 4, the digit in the position you’re rounding to stays the same.
If it’s a 5, 6, 7, 8, or 9, add 1 to the digit in the position you’re rounding to. -
Replace any digits to the right of the rounded digit with zeros. If any digits to the right of the rounded digit come after a decimal point, you can delete them.
A concert at an outdoor stage attracted a crowd of 91 627 people.
If we round to the nearest ten thousand, approximately how many people attended the concert?
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The digit in the ten thousands position in 91 627 is 9. |
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The digit to the right of the 9 in 91 627 is a 1, so we know that the 9 stays the same. |
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91 627 rounded to the nearest ten thousand is 90 000. |
Answer: Around 90 000 people went to the concert.
5th and 6th Grade
Rounding a number means giving a number that is close to the original number based on the desired place value.
Here’s how to round a number.
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Find the digit in the position you’re rounding to.
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Look at the digit directly to the right.
If it’s 0, 1, 2, 3, or 4, the digit in the position you’re rounding to stays the same.
If it’s a 5, 6, 7, 8, or 9, add 1 to the digit in the position you’re rounding to. -
Replace the digits to the right of the rounded digit with zeros.
If any digits to the right of the rounded digit come after a decimal point, you can delete them.
A concert at an outdoor stage attracted a crowd of 91 627 people. If we round to the nearest ten thousand, approximately how many people attended the concert?
|
The digit in the ten thousands position in 91 627 is 9. |
|
The digit to the right of the 9 in 91 627 is a 1, so we know that the 9 stays the same. |
|
91 627 rounded to the nearest ten thousand is 90 000. |
Answer: Around 90 000 people went to the concert
Lily spent $24.88 on candy. Approximately how much money is this if we round to the nearest unit?
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The digit in the ones position in 24.88 is 4. |
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The digit to the right of the 4 in 24.88 is an 8, so we know that we have to add 1 to the number 4. 4 + 1 = 5 |
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24.88 rounded to the nearest unit is 25. |
Answer: Lily spent approximately $25 on candy
When rounding up, we need to add a carry digit if the digit in the position we’re rounding to is a 9.
For example, let’s say we want to round 297 to the nearest ten.
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The digit in the tens position in 297 is 9. |
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The digit to the right of the 9 in 297 is a 7, so we know that we have to add 1 to the number 9. 9 + 1 = 10 So, we write a 0 in the tens place and add a carry digit of +1 to the hundreds position. +1 |
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297 rounded to the nearest ten is 300. |