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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 714 · 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 453 + 398? (a) 1100 (b) 700 (c) 900
  2. 2.Best estimate of 69 × 96? (a) 70000 (b) 7000 (c) 700
  3. 3.Best estimate of 32 × 74? (a) 21000 (b) 2100 (c) 210
  4. 4.Best estimate of 774 + 323? (a) 900 (b) 1100 (c) 1300
  5. 5.Best estimate of 244 + 224? (a) 400 (b) 600 (c) 200
  6. 6.Best estimate of 71 × 32? (a) 21000 (b) 210 (c) 2100
  7. 7.Best estimate of 36 × 90? (a) 3600 (b) 36000 (c) 360
  8. 8.Best estimate of 483 + 536? (a) 800 (b) 1000 (c) 1200
  9. 9.Best estimate of 58 × 32? (a) 1800 (b) 180 (c) 18000
  10. 10.Best estimate of 69 × 39? (a) 28000 (b) 280 (c) 2800
  11. 11.Best estimate of 79 × 23? (a) 1600 (b) 160 (c) 16000
  12. 12.Best estimate of 77 × 61? (a) 48000 (b) 480 (c) 4800
  13. 13.Best estimate of 23 × 18? (a) 40 (b) 400 (c) 4000
  14. 14.Best estimate of 36 × 52? (a) 2000 (b) 20000 (c) 200
  15. 15.Best estimate of 26 × 16? (a) 600 (b) 6000 (c) 60
  16. 16.Best estimate of 405 + 520? (a) 700 (b) 900 (c) 1100
  17. 17.Best estimate of 331 + 557? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 448 + 298? (a) 900 (b) 700 (c) 500
  19. 19.Best estimate of 14 × 46? (a) 5000 (b) 500 (c) 50
  20. 20.Best estimate of 53 × 21? (a) 100 (b) 1000 (c) 10000
  21. 21.Best estimate of 14 × 44? (a) 4000 (b) 400 (c) 40
  22. 22.Best estimate of 82 × 82? (a) 64000 (b) 640 (c) 6400
  23. 23.Best estimate of 68 × 48? (a) 350 (b) 3500 (c) 35000
  24. 24.Best estimate of 64 × 41? (a) 2400 (b) 240 (c) 24000
  25. 25.Best estimate of 53 × 13? (a) 5000 (b) 500 (c) 50
  26. 26.Best estimate of 93 × 48? (a) 4500 (b) 450 (c) 45000
  27. 27.Best estimate of 87 × 26? (a) 2700 (b) 27000 (c) 270
  28. 28.Best estimate of 132 + 655? (a) 1000 (b) 600 (c) 800
  29. 29.Best estimate of 745 + 602? (a) 1300 (b) 1500 (c) 1100
  30. 30.Best estimate of 479 + 254? (a) 600 (b) 800 (c) 1000
  31. 31.Best estimate of 42 × 21? (a) 800 (b) 8000 (c) 80
  32. 32.Best estimate of 48 × 72? (a) 35000 (b) 350 (c) 3500
  33. 33.Best estimate of 594 + 217? (a) 800 (b) 600 (c) 1000
  34. 34.Best estimate of 26 × 20? (a) 6000 (b) 60 (c) 600
  35. 35.Best estimate of 19 × 18? (a) 40 (b) 400 (c) 4000
  36. 36.Best estimate of 82 × 66? (a) 5600 (b) 56000 (c) 560
  37. 37.Best estimate of 56 × 70? (a) 4200 (b) 420 (c) 42000
  38. 38.Best estimate of 26 × 72? (a) 210 (b) 2100 (c) 21000
  39. 39.Best estimate of 602 + 496? (a) 1300 (b) 1100 (c) 900
  40. 40.Best estimate of 82 × 79? (a) 6400 (b) 64000 (c) 640

Answer key

  1. 900
  2. 7000
  3. 2100
  4. 1100
  5. 400
  6. 2100
  7. 3600
  8. 1000
  9. 1800
  10. 2800
  11. 1600
  12. 4800
  13. 400
  14. 2000
  15. 600
  16. 900
  17. 900
  18. 700
  19. 500
  20. 1000
  21. 400
  22. 6400
  23. 3500
  24. 2400
  25. 500
  26. 4500
  27. 2700
  28. 800
  29. 1300
  30. 800
  31. 800
  32. 3500
  33. 800
  34. 600
  35. 400
  36. 5600
  37. 4200
  38. 2100
  39. 1100
  40. 6400

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