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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 805 · 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 21 × 62? (a) 12000 (b) 1200 (c) 120
  2. 2.Best estimate of 47 × 71? (a) 3500 (b) 35000 (c) 350
  3. 3.Best estimate of 261 + 399? (a) 500 (b) 700 (c) 900
  4. 4.Best estimate of 576 + 557? (a) 1000 (b) 1200 (c) 1400
  5. 5.Best estimate of 217 + 572? (a) 600 (b) 1000 (c) 800
  6. 6.Best estimate of 58 × 87? (a) 54000 (b) 5400 (c) 540
  7. 7.Best estimate of 185 + 538? (a) 500 (b) 900 (c) 700
  8. 8.Best estimate of 26 × 57? (a) 1800 (b) 18000 (c) 180
  9. 9.Best estimate of 21 × 64? (a) 120 (b) 1200 (c) 12000
  10. 10.Best estimate of 89 × 78? (a) 72000 (b) 720 (c) 7200
  11. 11.Best estimate of 71 × 84? (a) 5600 (b) 560 (c) 56000
  12. 12.Best estimate of 298 + 352? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 30 × 70? (a) 2100 (b) 210 (c) 21000
  14. 14.Best estimate of 775 + 284? (a) 1300 (b) 900 (c) 1100
  15. 15.Best estimate of 22 × 34? (a) 60 (b) 6000 (c) 600
  16. 16.Best estimate of 757 + 569? (a) 1600 (b) 1200 (c) 1400
  17. 17.Best estimate of 854 + 280? (a) 1000 (b) 1200 (c) 1400
  18. 18.Best estimate of 451 + 270? (a) 800 (b) 600 (c) 1000
  19. 19.Best estimate of 166 + 489? (a) 500 (b) 900 (c) 700
  20. 20.Best estimate of 20 × 56? (a) 120 (b) 12000 (c) 1200
  21. 21.Best estimate of 62 × 34? (a) 1800 (b) 18000 (c) 180
  22. 22.Best estimate of 89 × 98? (a) 9000 (b) 900 (c) 90000
  23. 23.Best estimate of 608 + 680? (a) 1100 (b) 1500 (c) 1300
  24. 24.Best estimate of 16 × 31? (a) 60 (b) 600 (c) 6000
  25. 25.Best estimate of 434 + 867? (a) 1500 (b) 1300 (c) 1100
  26. 26.Best estimate of 88 × 51? (a) 45000 (b) 4500 (c) 450
  27. 27.Best estimate of 51 × 17? (a) 100 (b) 10000 (c) 1000
  28. 28.Best estimate of 732 + 854? (a) 1600 (b) 1400 (c) 1800
  29. 29.Best estimate of 44 × 21? (a) 800 (b) 8000 (c) 80
  30. 30.Best estimate of 42 × 29? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 440 + 534? (a) 900 (b) 700 (c) 1100
  32. 32.Best estimate of 798 + 825? (a) 1800 (b) 1600 (c) 1400
  33. 33.Best estimate of 233 + 594? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 163 + 240? (a) 600 (b) 400 (c) 200
  35. 35.Best estimate of 291 + 523? (a) 600 (b) 800 (c) 1000
  36. 36.Best estimate of 582 + 586? (a) 1200 (b) 1400 (c) 1000
  37. 37.Best estimate of 17 × 97? (a) 2000 (b) 20000 (c) 200
  38. 38.Best estimate of 90 × 43? (a) 360 (b) 3600 (c) 36000
  39. 39.Best estimate of 400 + 555? (a) 800 (b) 1200 (c) 1000
  40. 40.Best estimate of 36 × 46? (a) 200 (b) 2000 (c) 20000

Answer key

  1. 1200
  2. 3500
  3. 700
  4. 1200
  5. 800
  6. 5400
  7. 700
  8. 1800
  9. 1200
  10. 7200
  11. 5600
  12. 700
  13. 2100
  14. 1100
  15. 600
  16. 1400
  17. 1200
  18. 800
  19. 700
  20. 1200
  21. 1800
  22. 9000
  23. 1300
  24. 600
  25. 1300
  26. 4500
  27. 1000
  28. 1600
  29. 800
  30. 1200
  31. 900
  32. 1600
  33. 800
  34. 400
  35. 800
  36. 1200
  37. 2000
  38. 3600
  39. 1000
  40. 2000

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