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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 242 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 382 + 640? (a) 800 (b) 1200 (c) 1000
  2. 2.Best estimate of 88 × 48? (a) 4500 (b) 45000 (c) 450
  3. 3.Best estimate of 86 × 74? (a) 630 (b) 6300 (c) 63000
  4. 4.Best estimate of 318 + 719? (a) 800 (b) 1000 (c) 1200
  5. 5.Best estimate of 82 × 94? (a) 72000 (b) 720 (c) 7200
  6. 6.Best estimate of 83 × 16? (a) 160 (b) 1600 (c) 16000
  7. 7.Best estimate of 17 × 93? (a) 18000 (b) 180 (c) 1800
  8. 8.Best estimate of 287 + 579? (a) 1100 (b) 900 (c) 700
  9. 9.Best estimate of 448 + 583? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 598 + 518? (a) 1300 (b) 1100 (c) 900
  11. 11.Best estimate of 69 × 93? (a) 63000 (b) 630 (c) 6300
  12. 12.Best estimate of 68 × 61? (a) 4200 (b) 42000 (c) 420
  13. 13.Best estimate of 396 + 480? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 462 + 177? (a) 500 (b) 900 (c) 700
  15. 15.Best estimate of 73 × 36? (a) 2800 (b) 280 (c) 28000
  16. 16.Best estimate of 84 × 92? (a) 72000 (b) 7200 (c) 720
  17. 17.Best estimate of 31 × 24? (a) 6000 (b) 600 (c) 60
  18. 18.Best estimate of 97 × 46? (a) 50000 (b) 500 (c) 5000
  19. 19.Best estimate of 71 × 56? (a) 420 (b) 42000 (c) 4200
  20. 20.Best estimate of 67 × 73? (a) 490 (b) 4900 (c) 49000
  21. 21.Best estimate of 97 × 52? (a) 5000 (b) 500 (c) 50000
  22. 22.Best estimate of 28 × 67? (a) 210 (b) 21000 (c) 2100
  23. 23.Best estimate of 32 × 71? (a) 2100 (b) 210 (c) 21000
  24. 24.Best estimate of 451 + 381? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 135 + 168? (a) 100 (b) 500 (c) 300
  26. 26.Best estimate of 191 + 872? (a) 1100 (b) 900 (c) 1300
  27. 27.Best estimate of 480 + 555? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 216 + 865? (a) 1100 (b) 1300 (c) 900
  29. 29.Best estimate of 356 + 762? (a) 1200 (b) 1400 (c) 1000
  30. 30.Best estimate of 64 × 88? (a) 540 (b) 5400 (c) 54000
  31. 31.Best estimate of 697 + 612? (a) 1100 (b) 1300 (c) 1500
  32. 32.Best estimate of 73 × 67? (a) 4900 (b) 49000 (c) 490
  33. 33.Best estimate of 160 + 419? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 79 × 61? (a) 480 (b) 4800 (c) 48000
  35. 35.Best estimate of 456 + 853? (a) 1200 (b) 1600 (c) 1400
  36. 36.Best estimate of 94 × 37? (a) 3600 (b) 36000 (c) 360
  37. 37.Best estimate of 524 + 820? (a) 1100 (b) 1300 (c) 1500
  38. 38.Best estimate of 39 × 78? (a) 3200 (b) 32000 (c) 320
  39. 39.Best estimate of 43 × 80? (a) 3200 (b) 32000 (c) 320
  40. 40.Best estimate of 96 × 92? (a) 900 (b) 90000 (c) 9000

Answer key

  1. 1000
  2. 4500
  3. 6300
  4. 1000
  5. 7200
  6. 1600
  7. 1800
  8. 900
  9. 1000
  10. 1100
  11. 6300
  12. 4200
  13. 900
  14. 700
  15. 2800
  16. 7200
  17. 600
  18. 5000
  19. 4200
  20. 4900
  21. 5000
  22. 2100
  23. 2100
  24. 900
  25. 300
  26. 1100
  27. 1100
  28. 1100
  29. 1200
  30. 5400
  31. 1300
  32. 4900
  33. 600
  34. 4800
  35. 1400
  36. 3600
  37. 1300
  38. 3200
  39. 3200
  40. 9000

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