40 Place Value, Rounding & Adding Within 1000 Practice Questions & Answers

1. 1. Round 456 to the nearest ten. What number do you get?

   • A.400
   • B.460✓ Answer
   • C.450
   • D.500

   To round to the nearest ten, look at the ones digit: 456 is between 450 and 460, and a ones digit of 6 is 5 or more, so round up. 456 rounds to 460. Picking 500 means rounding to the nearest hundred instead of the nearest ten.

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2. 2. Round 456 to the nearest hundred. What number do you get?

   • A.400
   • B.460
   • C.450
   • D.500✓ Answer

   To round to the nearest hundred, look at the tens digit, not the ones digit: 456 is between 400 and 500, and its tens digit is 5, so round up. 456 rounds to 500. Picking 460 means rounding to the nearest ten instead.

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3. 3. Round 995 to the nearest ten. What number do you get?

   • A.1,000✓ Answer
   • B.995
   • C.990
   • D.900

   995 is between the tens 990 and 1,000, and it is exactly halfway, so it rounds up. The ten after 990 is 1,000, so 995 rounds to 1,000. Picking 990 comes from rounding the halfway number down.

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4. 4. Round 398 to the nearest ten. What number do you get?

   • A.400✓ Answer
   • B.390
   • C.490
   • D.398

   398 is between the tens 390 and 400, and its ones digit is 8, so it rounds up to the next ten. Adding one more ten to 39 tens makes 40 tens, which is 400. Picking 490 comes from adding 1 to the hundreds digit but keeping the 9 tens.

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5. 5. Which number rounds to 70 when you round it to the nearest ten?

   • A.65✓ Answer
   • B.76
   • C.64
   • D.75

   Find the two tens each number sits between and check its ones digit. 65 is halfway between 60 and 70, and halfway rounds up, so 65 rounds to 70. 75 is halfway between 70 and 80, so it rounds up to 80, not down to 70.

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6. 6. Which number rounds to 300 when you round it to the nearest hundred?

   • A.349✓ Answer
   • B.350
   • C.249
   • D.351

   Look at the tens digit to round to the nearest hundred. 349 has 4 tens, so it rounds down to 300. 350 is exactly halfway between 300 and 400, and halfway rounds up, so 350 rounds to 400, not 300.

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7. 7. You want to round 651 to the nearest hundred. Which sentence tells how to do it?

   • A.Look at the tens digit, 5, so 651 rounds up to 700.✓ Answer
   • B.Look at the tens digit, 5, so 651 rounds down to 600.
   • C.Look at the ones digit, 1, so 651 rounds down to 600.
   • D.Look at the ones digit, 1, so 651 rounds down to 650.

   When rounding to the nearest hundred, the tens digit decides. 651 has 5 tens, and 5 or more rounds up, so 651 rounds to 700. Looking at the ones digit, 1, is the most common mistake and gives 600.

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8. 8. What is 9 × 80?

   • A.7,200
   • B.89
   • C.72
   • D.720✓ Answer

   Think of 80 as 8 tens. 9 × 8 tens = 72 tens, and 72 tens is 720. Picking 72 forgets that the answer is counted in tens, not ones.

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9. 9. What is 5 × 40?

   • A.45
   • B.20
   • C.200✓ Answer
   • D.2,000

   Think of 40 as 4 tens. 5 × 4 tens = 20 tens, and 20 tens is 200. Picking 20 or 2,000 comes from dropping a zero or adding an extra one, because the fact 5 × 4 = 20 already ends in 0.

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10. 10. What number goes in the blank? 6 x ___ = 420

    • A.70✓ Answer
    • B.7
    • C.700
    • D.60

    Write 420 as 42 tens. Since 6 × 7 = 42, it takes 6 × 7 tens to make 42 tens, so the missing number is 70. Picking 7 gives only 6 × 7 = 42, which is 42 ones, not 420.

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11. 11. What number goes in the blank? ___ x 50 = 350

    • A.70
    • B.300
    • C.6
    • D.7✓ Answer

    Write 350 as 35 tens and 50 as 5 tens. Since 7 × 5 = 35, 7 × 5 tens = 35 tens, so the missing number is 7. Picking 70 gives 70 × 50 = 3,500, which is too big; picking 300 comes from subtracting 50 instead of multiplying.

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12. 12. What is 7 × 3 tens?

    • A.10 tens, or 100
    • B.21 hundreds, or 2,100
    • C.21 tens, or 210✓ Answer
    • D.21 ones, or 21

    Multiply the number of tens: 7 × 3 = 21, so 7 × 3 tens = 21 tens. Since each ten is 10, 21 tens is 210. Picking 10 tens comes from adding 7 + 3 instead of multiplying.

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13. 13. What is 70 × 3?

    • A.21
    • B.73
    • C.210✓ Answer
    • D.10

    You can multiply in either order, so 70 × 3 is the same as 3 × 7 tens. That is 21 tens, which is 210. Picking 21 forgets that 7 tens times 3 is counted in tens; picking 73 or 10 comes from adding instead of multiplying.

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14. 14. What is 8 × 50?

    • A.58
    • B.40
    • C.400✓ Answer
    • D.4,000

    Think of 50 as 5 tens. 8 × 5 tens = 40 tens, and 40 tens is 400. Picking 40 or 4,000 comes from losing or adding a zero, because the fact 8 × 5 = 40 already ends in 0.

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15. 15. Which shows why 8 × 60 = 480?

    • A.(8 + 6) × 10, which is 14 tens
    • B.(8 × 6) + 10, which is 58 ones
    • C.(8 × 6) × 10, which is 48 tens✓ Answer
    • D.(8 × 6) × 1, which is 48 ones

    60 is 6 × 10, so 8 × 60 = 8 × (6 × 10). You can group the factors differently: (8 × 6) × 10 = 48 × 10, which is 48 tens, or 480. Adding 10 instead of multiplying by 10 gives 58, which is far too small.

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16. 16. Ana has 6 boxes of crayons. Each box has 30 crayons. How many crayons does Ana have?

    • A.18 crayons
    • B.1,800 crayons
    • C.36 crayons
    • D.180 crayons✓ Answer

    Equal groups mean multiply: 6 boxes x 30 crayons. 30 is 3 tens, and 6 × 3 tens = 18 tens, which is 180 crayons. Picking 36 comes from adding 6 + 30 instead of multiplying.

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17. 17. What is 6 × 50?

    • A.56
    • B.300✓ Answer
    • C.350
    • D.30

    Think of 50 as 5 tens. 6 × 5 tens = 30 tens, and 30 tens is 300. Picking 30 comes from dropping a zero because the fact 6 × 5 = 30 already ends in 0; picking 350 comes from counting one group of 50 too many.

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18. 18. Kofi's garden has 9 rows. Each row has 20 plants. How many plants are in the garden?

    • A.180 plants✓ Answer
    • B.18 plants
    • C.1,800 plants
    • D.29 plants

    Rows with the same number in each row mean multiply: 9 × 20. 20 is 2 tens, and 9 × 2 tens = 18 tens, which is 180 plants. Picking 18 forgets that each row has 2 tens, not 2 ones.

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19. 19. What is 600 − 247?

    • A.353✓ Answer
    • B.447
    • C.363
    • D.453

    There are no ones or tens in 600, so regroup across the zeros: 600 becomes 5 hundreds, 9 tens and 10 ones. Then 10 − 7 = 3, 9 − 4 = 5 and 5 − 2 = 3, so the answer is 353. The tempting 447 comes from subtracting the smaller digit from the larger in each column (7 − 0 and 4 − 0) instead of regrouping.

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20. 20. What is 403 − 168?

    • A.365
    • B.235✓ Answer
    • C.335
    • D.245

    You cannot take 8 ones from 3 ones, and there are 0 tens, so regroup from the hundreds: 403 becomes 3 hundreds, 9 tens and 13 ones. Then 13 − 8 = 5, 9 − 6 = 3 and 3 − 1 = 2, giving 235. A common mistake is 365, which comes from subtracting the smaller digit from the larger in each column.

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21. 21. What is 368 + 275?

    • A.533
    • B.643✓ Answer
    • C.543
    • D.633

    Add each place and carry when a place reaches 10 or more. Ones: 8 + 5 = 13, write 3 and carry 1 ten. Tens: 6 + 7 + 1 = 14, write 4 and carry 1 hundred. Hundreds: 3 + 2 + 1 = 6, so the sum is 643; 533 is what you get if you forget both carries.

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22. 22. What is 523 − 268?

    • A.265
    • B.345
    • C.355
    • D.255✓ Answer

    This subtraction needs regrouping twice. Ones: 3 is less than 8, so trade a ten: 13 − 8 = 5. Tens: 1 left is less than 6, so trade a hundred: 11 − 6 = 5, and hundreds: 4 − 2 = 2, giving 255. The answer 345 comes from subtracting the smaller digit from the larger in every column.

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23. 23. What number goes in the blank? ___ + 247 = 610

    • A.437
    • B.857
    • C.373
    • D.363✓ Answer

    Addition and subtraction undo each other, so the missing part is 610 − 247. Regroup: 610 − 247 = 363, and checking 363 + 247 = 610 confirms it. Choosing 857 means adding the two numbers instead of finding the missing part.

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24. 24. What number makes this true? 815 = ___ + 396

    • A.519
    • B.419✓ Answer
    • C.581
    • D.429

    The equal sign means both sides have the same value, even when the total is on the left. The missing number is 815 − 396 = 419, and 419 + 396 = 815 checks it. The answer 581 comes from subtracting the smaller digit from the larger in each column.

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25. 25. What number goes in the blank? 652 − ___ = 389

    • A.337
    • B.263✓ Answer
    • C.363
    • D.273

    If you take away a number from 652 and 389 is left, the number taken away is 652 − 389. Regroup twice: 652 − 389 = 263, and 389 + 263 = 652 checks it. The answer 337 comes from subtracting the smaller digit from the larger in each column.

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26. 26. We know that 347 + 285 = 632. Which equation is also true?

    • A.632 + 285 = 347
    • B.632 − 285 = 347✓ Answer
    • C.347 − 285 = 632
    • D.632 − 347 = 258

    In a fact family, the total minus one part gives the other part. Here the total is 632 and the parts are 347 and 285, so 632 − 285 = 347. The equation 632 − 347 = 258 is tempting, but it swaps the digits of the real answer, 285.

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27. 27. Which expression has the same value as 398 + 245?

    • A.400 + 243✓ Answer
    • B.396 + 243
    • C.400 + 245
    • D.400 + 247

    To make a friendly number, move 2 from 245 over to 398: 398 + 2 = 400 and 245 − 2 = 243. The total stays the same, 643. The choice 400 + 245 is tempting, but it adds 2 without taking 2 away, so it equals 645.

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28. 28. Which expression has the same value as 503 − 298?

    • A.501 − 300
    • B.503 − 300
    • C.505 − 300✓ Answer
    • D.505 − 296

    In subtraction, adding the same amount to both numbers keeps the difference the same. Add 2 to each: 503 + 2 = 505 and 298 + 2 = 300, so 505 − 300 = 205, just like 503 − 298. The choice 501 − 300 is tempting, but it changes the numbers in opposite directions, which works for addition, not subtraction.

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29. 29. Mei adds 465 + 278 by place value. Hundreds: 400 + 200 = 600. Tens: 60 + 70 = 130. Ones: 5 + 8 = 13. What is the total?

    • A.633
    • B.743✓ Answer
    • C.643
    • D.733

    With partial sums, add all the parts at the end, keeping each part's full value. 600 + 130 + 13 = 743. The answer 733 is tempting, but it drops the 1 ten inside 13 and adds only 3.

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30. 30. Leo finds 702 − 495 by counting up from 495. He jumps 5 to get to 500, then 200 to get to 700, then 2 to get to 702. What is 702 − 495?

    • A.202
    • B.205
    • C.207✓ Answer
    • D.393

    When you count up to subtract, the answer is the total of all the jumps. 5 + 200 + 2 = 207, and 495 + 207 = 702 checks it. The answer 205 forgets the last jump of 2.

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31. 31. Sofia finds that 534 − 286 = 248. Which addition should she do to check her answer?

    • A.534 + 286
    • B.248 + 268
    • C.248 + 286✓ Answer
    • D.248 + 534

    Subtraction can be checked by adding the answer back to the number that was taken away; you should get the starting number. 248 + 286 = 534, so her answer is right. Adding 248 + 534 is a common mix-up: it adds the answer to the starting number instead of to the number taken away.

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32. 32. Which expression has the same value as 156 + 382?

    • A.382 − 156
    • B.382 + 156✓ Answer
    • C.382 + 165
    • D.328 + 156

    You can add two numbers in either order and get the same sum (the commutative property). So 382 + 156 = 156 + 382 = 538. The choice 382 − 156 is tempting, but switching the order only works for addition, and changing the sign changes the value.

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33. 33. Asha adds 275 + 125 + 340. She adds 275 + 125 first because they make a friendly number. What is the total?

    • A.730
    • B.640
    • C.750
    • D.740✓ Answer

    You can group addends in any way without changing the sum (the associative property). 275 + 125 = 400, and 400 + 340 = 740. The answer 640 comes from forgetting to carry the hundred in 275 + 125 and getting 300.

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34. 34. One digit is missing: 4_6 + 238 = 694. Which digit goes in the blank?

    • A.6
    • B.5✓ Answer
    • C.3
    • D.7

    Find the first number with subtraction: 694 − 238 = 456, so the missing tens digit is 5. Check: 6 + 8 = 14 carries 1 ten, and 5 + 3 + 1 = 9 tens. The digit 6 is tempting if you forget the ten carried from the ones (9 − 3 = 6).

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35. 35. A school library has 820 books. Students borrow 465 books. How many books are still in the library?

    • A.355 books✓ Answer
    • B.365 books
    • C.455 books
    • D.445 books

    Books leave the library, so subtract: 820 − 465. Regroup twice: 10 − 5 = 5 ones, 11 − 6 = 5 tens, 7 − 4 = 3 hundreds, so 355 books are left. The answer 445 comes from subtracting the smaller digit from the larger in each column.

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36. 36. Carlos read 286 pages in May and 347 pages in June. How many pages did he read in all?

    • A.523 pages
    • B.533 pages
    • C.633 pages✓ Answer
    • D.623 pages

    "In all" means put the two amounts together, so add: 286 + 347. Ones: 6 + 7 = 13, carry 1; tens: 8 + 4 + 1 = 13, carry 1; hundreds: 2 + 3 + 1 = 6, so 633 pages. The answer 623 forgets the ten carried from the ones.

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37. 37. For the school play, third graders sold 512 tickets and fourth graders sold 375 tickets. How many more tickets did the third graders sell?

    • A.237 tickets
    • B.887 tickets
    • C.263 tickets
    • D.137 tickets✓ Answer

    "How many more" compares two amounts, so subtract the smaller from the larger: 512 − 375. Regroup twice: 12 − 5 = 7, 10 − 7 = 3, 4 − 3 = 1, giving 137 tickets. Choosing 887 means adding the two amounts instead of comparing them.

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38. 38. A bar graph shows cans collected for a food drive: Room 8 collected 450 cans and Room 9 collected 285 cans. How many fewer cans did Room 9 collect than Room 8?

    • A.265 cans
    • B.235 cans
    • C.175 cans
    • D.165 cans✓ Answer

    "How many fewer" compares two amounts, so subtract: 450 − 285. Regroup twice: 10 − 5 = 5 ones, 14 − 8 = 6 tens, 3 − 2 = 1 hundred, so 165 cans. The answer 175 comes from regrouping the tens without first lowering them from 5 to 4.

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39. 39. What is 705 − 248?

    • A.467
    • B.557
    • C.457✓ Answer
    • D.543

    There are 0 tens, so regroup from the hundreds: 705 becomes 6 hundreds, 9 tens and 15 ones. Then 15 − 8 = 7, 9 − 4 = 5 and 6 − 2 = 4, giving 457. The answer 557 is tempting if you forget that the hundreds dropped from 7 to 6.

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40. 40. Which expression has the same value as 724 − 389?

    • A.724 − 400
    • B.723 − 390
    • C.725 − 388
    • D.725 − 390✓ Answer

    Adding the same amount to both numbers keeps a difference the same. Add 1 to each: 724 + 1 = 725 and 389 + 1 = 390, so 725 − 390 = 335, just like 724 − 389. The choice 723 − 390 is tempting, but moving the numbers in opposite directions changes the difference to 333.

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Practice questions written from the California Common Core State Standards for Mathematics for grade 3, the content the CAASPP Smarter Balanced math test measures. This site is not affiliated with or endorsed by the California Department of Education, ETS or the Smarter Balanced Assessment Consortium, and these are not real test questions. The real test is taken on a computer and also uses question types such as typing a number, choosing several answers and dragging items; we practice the same skills with multiple choice. For the official interface, use the CAASPP practice and training tests. CAASPP practice and training tests →