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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 742 · 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 38 × 34? (a) 120 (b) 1200 (c) 12000
  2. 2.Best estimate of 32 × 26? (a) 90 (b) 9000 (c) 900
  3. 3.Best estimate of 47 × 20? (a) 100 (b) 1000 (c) 10000
  4. 4.Best estimate of 572 + 516? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 449 + 600? (a) 800 (b) 1200 (c) 1000
  6. 6.Best estimate of 51 × 77? (a) 40000 (b) 400 (c) 4000
  7. 7.Best estimate of 44 × 31? (a) 120 (b) 12000 (c) 1200
  8. 8.Best estimate of 96 × 62? (a) 60000 (b) 600 (c) 6000
  9. 9.Best estimate of 644 + 427? (a) 800 (b) 1000 (c) 1200
  10. 10.Best estimate of 755 + 582? (a) 1600 (b) 1400 (c) 1200
  11. 11.Best estimate of 84 × 28? (a) 240 (b) 24000 (c) 2400
  12. 12.Best estimate of 26 × 68? (a) 21000 (b) 210 (c) 2100
  13. 13.Best estimate of 801 + 231? (a) 1000 (b) 800 (c) 1200
  14. 14.Best estimate of 623 + 431? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 211 + 427? (a) 800 (b) 400 (c) 600
  16. 16.Best estimate of 495 + 486? (a) 1000 (b) 800 (c) 1200
  17. 17.Best estimate of 79 × 46? (a) 40000 (b) 400 (c) 4000
  18. 18.Best estimate of 92 × 32? (a) 2700 (b) 27000 (c) 270
  19. 19.Best estimate of 93 × 92? (a) 81000 (b) 8100 (c) 810
  20. 20.Best estimate of 83 × 30? (a) 240 (b) 2400 (c) 24000
  21. 21.Best estimate of 14 × 41? (a) 40 (b) 400 (c) 4000
  22. 22.Best estimate of 422 + 184? (a) 600 (b) 800 (c) 400
  23. 23.Best estimate of 72 × 51? (a) 35000 (b) 3500 (c) 350
  24. 24.Best estimate of 306 + 795? (a) 900 (b) 1100 (c) 1300
  25. 25.Best estimate of 14 × 62? (a) 60 (b) 6000 (c) 600
  26. 26.Best estimate of 339 + 286? (a) 400 (b) 800 (c) 600
  27. 27.Best estimate of 345 + 291? (a) 600 (b) 400 (c) 800
  28. 28.Best estimate of 86 × 94? (a) 810 (b) 8100 (c) 81000
  29. 29.Best estimate of 53 × 24? (a) 10000 (b) 100 (c) 1000
  30. 30.Best estimate of 265 + 127? (a) 400 (b) 600 (c) 200
  31. 31.Best estimate of 49 × 94? (a) 4500 (b) 450 (c) 45000
  32. 32.Best estimate of 133 + 343? (a) 200 (b) 600 (c) 400
  33. 33.Best estimate of 81 × 73? (a) 5600 (b) 56000 (c) 560
  34. 34.Best estimate of 98 × 76? (a) 8000 (b) 800 (c) 80000
  35. 35.Best estimate of 59 × 21? (a) 1200 (b) 12000 (c) 120
  36. 36.Best estimate of 56 × 73? (a) 4200 (b) 42000 (c) 420
  37. 37.Best estimate of 239 + 193? (a) 600 (b) 200 (c) 400
  38. 38.Best estimate of 427 + 387? (a) 800 (b) 600 (c) 1000
  39. 39.Best estimate of 289 + 465? (a) 600 (b) 800 (c) 1000
  40. 40.Best estimate of 604 + 120? (a) 900 (b) 500 (c) 700

Answer key

  1. 1200
  2. 900
  3. 1000
  4. 1100
  5. 1000
  6. 4000
  7. 1200
  8. 6000
  9. 1000
  10. 1400
  11. 2400
  12. 2100
  13. 1000
  14. 1000
  15. 600
  16. 1000
  17. 4000
  18. 2700
  19. 8100
  20. 2400
  21. 400
  22. 600
  23. 3500
  24. 1100
  25. 600
  26. 600
  27. 600
  28. 8100
  29. 1000
  30. 400
  31. 4500
  32. 400
  33. 5600
  34. 8000
  35. 1200
  36. 4200
  37. 400
  38. 800
  39. 800
  40. 700

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