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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 31 · 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 875 + 210? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 221 + 183? (a) 200 (b) 600 (c) 400
  3. 3.Best estimate of 128 + 121? (a) 0 (b) 400 (c) 200
  4. 4.Best estimate of 372 + 385? (a) 800 (b) 1000 (c) 600
  5. 5.Best estimate of 68 × 66? (a) 490 (b) 49000 (c) 4900
  6. 6.Best estimate of 33 × 96? (a) 300 (b) 3000 (c) 30000
  7. 7.Best estimate of 474 + 297? (a) 600 (b) 1000 (c) 800
  8. 8.Best estimate of 437 + 805? (a) 1200 (b) 1400 (c) 1000
  9. 9.Best estimate of 312 + 417? (a) 500 (b) 900 (c) 700
  10. 10.Best estimate of 500 + 563? (a) 1300 (b) 900 (c) 1100
  11. 11.Best estimate of 283 + 404? (a) 900 (b) 500 (c) 700
  12. 12.Best estimate of 412 + 704? (a) 1100 (b) 900 (c) 1300
  13. 13.Best estimate of 758 + 478? (a) 1500 (b) 1100 (c) 1300
  14. 14.Best estimate of 81 × 27? (a) 24000 (b) 2400 (c) 240
  15. 15.Best estimate of 31 × 48? (a) 1500 (b) 15000 (c) 150
  16. 16.Best estimate of 124 + 719? (a) 1000 (b) 800 (c) 600
  17. 17.Best estimate of 84 × 92? (a) 7200 (b) 72000 (c) 720
  18. 18.Best estimate of 13 × 86? (a) 90 (b) 9000 (c) 900
  19. 19.Best estimate of 66 × 59? (a) 4200 (b) 420 (c) 42000
  20. 20.Best estimate of 673 + 793? (a) 1500 (b) 1300 (c) 1700
  21. 21.Best estimate of 70 × 73? (a) 490 (b) 49000 (c) 4900
  22. 22.Best estimate of 27 × 16? (a) 60 (b) 6000 (c) 600
  23. 23.Best estimate of 581 + 351? (a) 1200 (b) 800 (c) 1000
  24. 24.Best estimate of 20 × 62? (a) 12000 (b) 120 (c) 1200
  25. 25.Best estimate of 822 + 209? (a) 1200 (b) 800 (c) 1000
  26. 26.Best estimate of 92 × 63? (a) 54000 (b) 540 (c) 5400
  27. 27.Best estimate of 233 + 170? (a) 200 (b) 600 (c) 400
  28. 28.Best estimate of 202 + 610? (a) 600 (b) 1000 (c) 800
  29. 29.Best estimate of 23 × 96? (a) 2000 (b) 20000 (c) 200
  30. 30.Best estimate of 726 + 851? (a) 1800 (b) 1600 (c) 1400
  31. 31.Best estimate of 86 × 59? (a) 540 (b) 54000 (c) 5400
  32. 32.Best estimate of 170 + 583? (a) 800 (b) 1000 (c) 600
  33. 33.Best estimate of 848 + 324? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 43 × 16? (a) 8000 (b) 80 (c) 800
  35. 35.Best estimate of 76 × 28? (a) 240 (b) 2400 (c) 24000
  36. 36.Best estimate of 620 + 137? (a) 500 (b) 700 (c) 900
  37. 37.Best estimate of 12 × 18? (a) 2000 (b) 20 (c) 200
  38. 38.Best estimate of 66 × 47? (a) 35000 (b) 350 (c) 3500
  39. 39.Best estimate of 771 + 435? (a) 1000 (b) 1200 (c) 1400
  40. 40.Best estimate of 26 × 16? (a) 60 (b) 6000 (c) 600

Answer key

  1. 1100
  2. 400
  3. 200
  4. 800
  5. 4900
  6. 3000
  7. 800
  8. 1200
  9. 700
  10. 1100
  11. 700
  12. 1100
  13. 1300
  14. 2400
  15. 1500
  16. 800
  17. 7200
  18. 900
  19. 4200
  20. 1500
  21. 4900
  22. 600
  23. 1000
  24. 1200
  25. 1000
  26. 5400
  27. 400
  28. 800
  29. 2000
  30. 1600
  31. 5400
  32. 800
  33. 1100
  34. 800
  35. 2400
  36. 700
  37. 200
  38. 3500
  39. 1200
  40. 600

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