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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 959 · 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 625 + 134? (a) 700 (b) 900 (c) 500
  2. 2.Best estimate of 766 + 174? (a) 1000 (b) 800 (c) 1200
  3. 3.Best estimate of 861 + 183? (a) 900 (b) 1300 (c) 1100
  4. 4.Best estimate of 24 × 37? (a) 8000 (b) 80 (c) 800
  5. 5.Best estimate of 28 × 17? (a) 60 (b) 6000 (c) 600
  6. 6.Best estimate of 89 × 52? (a) 45000 (b) 4500 (c) 450
  7. 7.Best estimate of 742 + 441? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 40 × 50? (a) 20000 (b) 2000 (c) 200
  9. 9.Best estimate of 59 × 58? (a) 36000 (b) 3600 (c) 360
  10. 10.Best estimate of 604 + 714? (a) 1100 (b) 1300 (c) 1500
  11. 11.Best estimate of 61 × 12? (a) 600 (b) 6000 (c) 60
  12. 12.Best estimate of 87 × 12? (a) 90 (b) 900 (c) 9000
  13. 13.Best estimate of 212 + 401? (a) 400 (b) 600 (c) 800
  14. 14.Best estimate of 186 + 318? (a) 300 (b) 700 (c) 500
  15. 15.Best estimate of 26 × 37? (a) 12000 (b) 120 (c) 1200
  16. 16.Best estimate of 72 × 87? (a) 63000 (b) 6300 (c) 630
  17. 17.Best estimate of 44 × 80? (a) 320 (b) 32000 (c) 3200
  18. 18.Best estimate of 246 + 387? (a) 400 (b) 800 (c) 600
  19. 19.Best estimate of 268 + 830? (a) 900 (b) 1100 (c) 1300
  20. 20.Best estimate of 418 + 276? (a) 500 (b) 900 (c) 700
  21. 21.Best estimate of 245 + 646? (a) 600 (b) 1000 (c) 800
  22. 22.Best estimate of 73 × 19? (a) 140 (b) 14000 (c) 1400
  23. 23.Best estimate of 427 + 803? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 808 + 361? (a) 1200 (b) 1400 (c) 1000
  25. 25.Best estimate of 265 + 159? (a) 500 (b) 300 (c) 700
  26. 26.Best estimate of 88 × 16? (a) 18000 (b) 180 (c) 1800
  27. 27.Best estimate of 30 × 16? (a) 6000 (b) 60 (c) 600
  28. 28.Best estimate of 70 × 73? (a) 49000 (b) 4900 (c) 490
  29. 29.Best estimate of 94 × 68? (a) 630 (b) 63000 (c) 6300
  30. 30.Best estimate of 16 × 53? (a) 100 (b) 10000 (c) 1000
  31. 31.Best estimate of 46 × 37? (a) 200 (b) 20000 (c) 2000
  32. 32.Best estimate of 818 + 333? (a) 1100 (b) 900 (c) 1300
  33. 33.Best estimate of 417 + 707? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 30 × 20? (a) 600 (b) 6000 (c) 60
  35. 35.Best estimate of 86 × 20? (a) 1800 (b) 180 (c) 18000
  36. 36.Best estimate of 96 × 88? (a) 9000 (b) 90000 (c) 900
  37. 37.Best estimate of 274 + 313? (a) 600 (b) 800 (c) 400
  38. 38.Best estimate of 59 × 20? (a) 1200 (b) 12000 (c) 120
  39. 39.Best estimate of 818 + 558? (a) 1600 (b) 1400 (c) 1200
  40. 40.Best estimate of 386 + 703? (a) 900 (b) 1300 (c) 1100

Answer key

  1. 700
  2. 1000
  3. 1100
  4. 800
  5. 600
  6. 4500
  7. 1100
  8. 2000
  9. 3600
  10. 1300
  11. 600
  12. 900
  13. 600
  14. 500
  15. 1200
  16. 6300
  17. 3200
  18. 600
  19. 1100
  20. 700
  21. 800
  22. 1400
  23. 1200
  24. 1200
  25. 500
  26. 1800
  27. 600
  28. 4900
  29. 6300
  30. 1000
  31. 2000
  32. 1100
  33. 1100
  34. 600
  35. 1800
  36. 9000
  37. 600
  38. 1200
  39. 1400
  40. 1100

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