4th Grade Rounding Whole Numbers Worksheet Answer Key (PDF)

4th grade rounding worksheet answers – Maths PDF

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This 4th grade rounding worksheet answers covers rounding whole numbers (Common Core 4.NBT.A.3), with a free PDF to print.

Key takeaway: This answer key helps fourth grade students and parents check rounding and estimation work.

Topic: Rounding Whole Numbers (4th grade)
Content: Step-by-step answers to 20 worksheet problems
Standards: 4.NBT.A.3
Answers: Every step shown, with the method to review
Format: Free printable PDF, US Letter, black and white

This answer key helps fourth grade students and parents check rounding and estimation work. Each solution names the rounding place, shows the digit to its right, and gives the rounded number, so the reason is clear.

The key covers all 20 problems, including the number line in problem 7 and the halfway numbers in problems 4 and 10. Also, estimate problems show the rounded numbers and the final calculation. If your answer differs, check the digit to the right of the rounding place first. Then, plan about 15 minutes to compare and fix your work.

Use this answer key to check each rounding problem. Every solution names the rounding place, shows the digit to its right, and gives the rounded number in bold. Estimates are compared with exact answers so you can see why they are reasonable.

Grade 4 · Common Core State Standards: 4.NBT.A.3

4th grade rounding worksheet answers: worksheet problems 1 to 10

1 – Nearest ten

Also, the tens digit is 8. The digit to its right is 3, which is less than 5, so keep 8.

$683$ rounds to $680$.

2 – Nearest hundred

Also, the hundreds digit is 2. The digit to its right is 5, so round up to 3.

$4,300$

3 – Nearest thousand

Also, the thousands digit is 8. The digit to its right is 7, so round up to 9.

$39,000$

4 – Halfway number

2,500 is exactly halfway, so it rounds up to 3,000.

Also, the number line shows 2,500 exactly halfway between 2,000 and 3,000. By the rule, halfway numbers round up.

$3,000$

5 – Nearest ten thousand

Also, the ten thousands digit is 7. The digit to its right is 6, so round up to 8.

$80,000$

6 – Nearest hundred thousand

Also, the hundred thousands digit is 4. The digit to its right is 8, so round up to 5.

$500,000$

7 – Use the number line

347 is right of the halfway point 345, so it rounds to 350.

347 is 7 steps from 340 and 3 steps from 350, so it is closer to 350.

$350$

Worksheet problem 8 and after

8 – Rounding a 9

Also, the tens digit is 9 and the digit to its right is 9, so round up. 9 tens plus 1 ten is 10 tens, which carries.

$990 + 10 = 1{,}000$

$1,000$

9 – Carrying across thousands

9,960 is closer to 10,000 than to 9,900.

Also, the hundreds digit is 9. The digit to its right is 6, so round up. 99 hundreds plus 1 hundred is 100 hundreds.

$10,000$

10 – Another halfway number

Also, the thousands digit is 4. The digit to its right is 5, so round up to 5.

$25,000$

Worksheet problems 11 and up

11 – Three places

Ten thousand: the digit 5 is followed by 8, so round up to $360,000$.

Thousand: the digit 8 is followed by 4, so keep it: $358,000$.

Hundred: the digit 4 is followed by 2, so keep it: $358,400$.

$360,000$; $358,000$; $358,400$

12 – Smallest and greatest

Numbers from halfway below 700 up to just under halfway above 700 round to 700. Halfway below is 650 and halfway above is 750.

650 rounds up to 700. 749 rounds down to 700. 750 rounds up to 800.

Smallest: 650. Greatest: 749.

13 – Estimate a sum

$4,862$ rounds to $5,000$. $2,139$ rounds to $2,000$.

$5{,}000 + 2{,}000 = 7{,}000$

about $7,000$

14 – Estimate a difference

$52,816$ rounds to $50,000$. $19,374$ rounds to $20,000$.

$50{,}000 – 20{,}000 = 30{,}000$

about $30,000$

15 – Stadium crowd

Thousand: the 8 is followed by 7, so round up to 19: $19,000$.

Hundred: the 7 is followed by 4, so keep it: $18,700$.

$19,000$; $18,700$

16 – Road trip estimate

$1,286$ rounds to $1,300$. $874$ rounds to $900$.

Estimate: $1{,}300 + 900 = 2{,}200$.

Exact: $1{,}286 + 874 = 2{,}160$.

The difference is only 40 miles, so the exact answer is reasonable.

Estimate $2,200$ miles; exact $2,160$ miles

Worksheet problem 17 and after

17 – Fundraiser change

$\$3,482.00$ rounds to $\$3,500.00$. $\$2,961.00$ rounds to $\$3,000.00$.

Estimate: $3{,}500 – 3{,}000 = 500$.

Exact: $3{,}482 – 2{,}961 = 521$.

about $\$500.00$ more; exactly $\$521.00$ more

18 – Could it be the number?

A number rounds to $40,000$ when it is from $35,000$ up to $44,999$.

35,999 is in the range (round up from 35,000). 38,420 is in the range. 44,100 is in the range. 45,000 rounds up to 50,000, so it is not.

35,999, 38,420, and 44,100

19 – Is $5,000 enough?

Nearest thousand: $2{,}000 + 2{,}000 + 1{,}000 = 5{,}000$. This estimate says she has exactly enough, which is not helpful.

Nearest hundred: $1{,}900 + 2{,}200 + 1{,}100 = 5{,}200$. This estimate says she does not have enough.

Exact: $1{,}879 + 2{,}246 + 1{,}125 = 5{,}250$.

Since $\$5,250.00$ is more than $\$5,000.00$, she is short by $\$250.00$. The hundreds estimate is more useful.

Nearest hundred; exact total $\$5,250.00$

20 – Find the mistake

The tens digit is 9. The digit to its right is 5, which is 5 or more, so the 9 must round up. Liam kept it instead.

Correct: $6{,}490 + 10 = 6{,}500$, so $6,495$ rounds to $6,500$.

Nearest hundred: the hundreds digit is 4 and the digit to its right is 9, so round up to $6,500$.

$6,500$ for both

Key facts behind this 4th grade rounding worksheet answers

Key facts

To round, look at the digit to the right of the place you want.
Digits 5, 6, 7, 8, and 9 round up. Digits 0, 1, 2, 3, and 4 round down.
A number exactly halfway between two multiples rounds up: 2,500 rounds to 3,000.
Then, a 9 can carry: 9,960 rounds to 10,000 at the nearest hundred.
To estimate, round every number to the same place, then add or subtract.

Common mistakes with this 4th grade rounding worksheet answers

Students compare only the rounded number. Instead, check which digit you used to decide, because that digit explains the answer.
Students skip the carry in problems 8 and 9. Instead, the key shows each place changing, which is why 999 becomes 1,000.
Students write the estimate but not the rounded numbers. The rounded numbers are part of the answer, so list them.
Students ignore the explanation in problem 20. Also, the key says why the ones digit 5 rounds up.

How to use these solutions

Underline the rounding place in your own work and compare it with the key. Then, using the wrong place causes most errors.
Redo each missed problem on a number line. Finally, the line shows which multiple is closer. Repeat this habit on every problem for the best results.
Parents can ask the child why a number halfway between two multiples rounds up. Repeat this habit on every problem for the best results.

Download the 4th grade rounding worksheet answers as a PDF with the button below and keep it with your notes.

4th grade rounding worksheet answers: frequently asked questions

Why does 999 round to 1,000 and not 990?

Rounding 999 to the nearest ten asks which multiple of ten is closest. The ones digit is 9, so round up to the next ten. Since 999 is 9 tens and 9 ones, adding 1 makes 10 tens, which is 1,000.

How do you round 358,429 to three places?

Round to each place separately from the original number. Also, to the nearest ten thousand, it is 360,000. So, to the nearest thousand, it is 358,000. To the nearest hundred, it is 358,400. Never round the rounded number again.

Is the estimate in problem 13 the same as the exact answer?

No. Rounding 4,862 and 2,139 to the nearest thousand gives 5,000 plus 2,000, or 7,000. The exact sum is 7,001, so the estimate is very close. An estimate only needs to be near the answer.

All Grade 4 chapters: Grade 4 math.

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