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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 27 · 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 647 + 290? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 844 + 322? (a) 1100 (b) 900 (c) 1300
  3. 3.Best estimate of 426 + 647? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 50 × 61? (a) 30000 (b) 300 (c) 3000
  5. 5.Best estimate of 728 + 369? (a) 1100 (b) 900 (c) 1300
  6. 6.Best estimate of 20 × 97? (a) 2000 (b) 200 (c) 20000
  7. 7.Best estimate of 184 + 727? (a) 900 (b) 700 (c) 1100
  8. 8.Best estimate of 301 + 280? (a) 400 (b) 600 (c) 800
  9. 9.Best estimate of 43 × 36? (a) 16000 (b) 160 (c) 1600
  10. 10.Best estimate of 39 × 82? (a) 3200 (b) 320 (c) 32000
  11. 11.Best estimate of 17 × 63? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 27 × 43? (a) 1200 (b) 12000 (c) 120
  13. 13.Best estimate of 46 × 87? (a) 4500 (b) 45000 (c) 450
  14. 14.Best estimate of 359 + 711? (a) 1300 (b) 900 (c) 1100
  15. 15.Best estimate of 836 + 491? (a) 1300 (b) 1500 (c) 1100
  16. 16.Best estimate of 202 + 365? (a) 800 (b) 400 (c) 600
  17. 17.Best estimate of 57 × 62? (a) 3600 (b) 36000 (c) 360
  18. 18.Best estimate of 21 × 50? (a) 10000 (b) 100 (c) 1000
  19. 19.Best estimate of 29 × 78? (a) 24000 (b) 240 (c) 2400
  20. 20.Best estimate of 21 × 98? (a) 2000 (b) 20000 (c) 200
  21. 21.Best estimate of 151 + 317? (a) 500 (b) 300 (c) 700
  22. 22.Best estimate of 20 × 21? (a) 400 (b) 40 (c) 4000
  23. 23.Best estimate of 91 × 33? (a) 270 (b) 2700 (c) 27000
  24. 24.Best estimate of 784 + 594? (a) 1200 (b) 1600 (c) 1400
  25. 25.Best estimate of 76 × 98? (a) 8000 (b) 80000 (c) 800
  26. 26.Best estimate of 44 × 12? (a) 4000 (b) 40 (c) 400
  27. 27.Best estimate of 709 + 527? (a) 1200 (b) 1000 (c) 1400
  28. 28.Best estimate of 48 × 90? (a) 4500 (b) 45000 (c) 450
  29. 29.Best estimate of 18 × 43? (a) 800 (b) 80 (c) 8000
  30. 30.Best estimate of 758 + 192? (a) 1000 (b) 1200 (c) 800
  31. 31.Best estimate of 17 × 87? (a) 18000 (b) 1800 (c) 180
  32. 32.Best estimate of 310 + 567? (a) 900 (b) 1100 (c) 700
  33. 33.Best estimate of 860 + 500? (a) 1600 (b) 1400 (c) 1200
  34. 34.Best estimate of 44 × 63? (a) 2400 (b) 24000 (c) 240
  35. 35.Best estimate of 326 + 676? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 56 × 43? (a) 240 (b) 24000 (c) 2400
  37. 37.Best estimate of 18 × 30? (a) 6000 (b) 60 (c) 600
  38. 38.Best estimate of 13 × 96? (a) 1000 (b) 100 (c) 10000
  39. 39.Best estimate of 72 × 61? (a) 4200 (b) 420 (c) 42000
  40. 40.Best estimate of 618 + 739? (a) 1500 (b) 1100 (c) 1300

Answer key

  1. 900
  2. 1100
  3. 1000
  4. 3000
  5. 1100
  6. 2000
  7. 900
  8. 600
  9. 1600
  10. 3200
  11. 1200
  12. 1200
  13. 4500
  14. 1100
  15. 1300
  16. 600
  17. 3600
  18. 1000
  19. 2400
  20. 2000
  21. 500
  22. 400
  23. 2700
  24. 1400
  25. 8000
  26. 400
  27. 1200
  28. 4500
  29. 800
  30. 1000
  31. 1800
  32. 900
  33. 1400
  34. 2400
  35. 1000
  36. 2400
  37. 600
  38. 1000
  39. 4200
  40. 1300

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