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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 155 · 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 861 + 132? (a) 800 (b) 1000 (c) 1200
  2. 2.Best estimate of 63 × 62? (a) 3600 (b) 360 (c) 36000
  3. 3.Best estimate of 61 × 92? (a) 5400 (b) 540 (c) 54000
  4. 4.Best estimate of 36 × 80? (a) 32000 (b) 320 (c) 3200
  5. 5.Best estimate of 483 + 666? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 424 + 807? (a) 1200 (b) 1400 (c) 1000
  7. 7.Best estimate of 88 × 22? (a) 1800 (b) 18000 (c) 180
  8. 8.Best estimate of 208 + 135? (a) 300 (b) 500 (c) 100
  9. 9.Best estimate of 37 × 58? (a) 24000 (b) 2400 (c) 240
  10. 10.Best estimate of 26 × 69? (a) 2100 (b) 21000 (c) 210
  11. 11.Best estimate of 22 × 69? (a) 1400 (b) 140 (c) 14000
  12. 12.Best estimate of 325 + 666? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 31 × 17? (a) 60 (b) 6000 (c) 600
  14. 14.Best estimate of 63 × 46? (a) 3000 (b) 30000 (c) 300
  15. 15.Best estimate of 97 × 94? (a) 90000 (b) 9000 (c) 900
  16. 16.Best estimate of 229 + 663? (a) 1100 (b) 700 (c) 900
  17. 17.Best estimate of 658 + 783? (a) 1300 (b) 1500 (c) 1700
  18. 18.Best estimate of 93 × 12? (a) 900 (b) 90 (c) 9000
  19. 19.Best estimate of 685 + 478? (a) 1400 (b) 1200 (c) 1000
  20. 20.Best estimate of 828 + 410? (a) 1000 (b) 1400 (c) 1200
  21. 21.Best estimate of 26 × 50? (a) 15000 (b) 1500 (c) 150
  22. 22.Best estimate of 368 + 764? (a) 1200 (b) 1000 (c) 1400
  23. 23.Best estimate of 49 × 83? (a) 40000 (b) 400 (c) 4000
  24. 24.Best estimate of 57 × 47? (a) 3000 (b) 300 (c) 30000
  25. 25.Best estimate of 872 + 216? (a) 1300 (b) 900 (c) 1100
  26. 26.Best estimate of 31 × 93? (a) 27000 (b) 2700 (c) 270
  27. 27.Best estimate of 242 + 665? (a) 700 (b) 1100 (c) 900
  28. 28.Best estimate of 84 × 93? (a) 720 (b) 7200 (c) 72000
  29. 29.Best estimate of 94 × 63? (a) 540 (b) 5400 (c) 54000
  30. 30.Best estimate of 566 + 617? (a) 1400 (b) 1200 (c) 1000
  31. 31.Best estimate of 338 + 793? (a) 900 (b) 1100 (c) 1300
  32. 32.Best estimate of 57 × 72? (a) 42000 (b) 4200 (c) 420
  33. 33.Best estimate of 73 × 39? (a) 2800 (b) 28000 (c) 280
  34. 34.Best estimate of 63 × 18? (a) 120 (b) 1200 (c) 12000
  35. 35.Best estimate of 77 × 97? (a) 8000 (b) 80000 (c) 800
  36. 36.Best estimate of 96 × 72? (a) 7000 (b) 70000 (c) 700
  37. 37.Best estimate of 18 × 64? (a) 1200 (b) 120 (c) 12000
  38. 38.Best estimate of 51 × 34? (a) 15000 (b) 1500 (c) 150
  39. 39.Best estimate of 74 × 98? (a) 70000 (b) 700 (c) 7000
  40. 40.Best estimate of 261 + 872? (a) 1000 (b) 1400 (c) 1200

Answer key

  1. 1000
  2. 3600
  3. 5400
  4. 3200
  5. 1200
  6. 1200
  7. 1800
  8. 300
  9. 2400
  10. 2100
  11. 1400
  12. 1000
  13. 600
  14. 3000
  15. 9000
  16. 900
  17. 1500
  18. 900
  19. 1200
  20. 1200
  21. 1500
  22. 1200
  23. 4000
  24. 3000
  25. 1100
  26. 2700
  27. 900
  28. 7200
  29. 5400
  30. 1200
  31. 1100
  32. 4200
  33. 2800
  34. 1200
  35. 8000
  36. 7000
  37. 1200
  38. 1500
  39. 7000
  40. 1200

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