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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 480 · 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 724 + 506? (a) 1400 (b) 1200 (c) 1000
  2. 2.Best estimate of 54 × 74? (a) 35000 (b) 350 (c) 3500
  3. 3.Best estimate of 46 × 52? (a) 25000 (b) 250 (c) 2500
  4. 4.Best estimate of 83 × 86? (a) 720 (b) 72000 (c) 7200
  5. 5.Best estimate of 81 × 69? (a) 560 (b) 56000 (c) 5600
  6. 6.Best estimate of 32 × 80? (a) 2400 (b) 240 (c) 24000
  7. 7.Best estimate of 744 + 401? (a) 1300 (b) 900 (c) 1100
  8. 8.Best estimate of 58 × 16? (a) 120 (b) 1200 (c) 12000
  9. 9.Best estimate of 404 + 749? (a) 1300 (b) 1100 (c) 900
  10. 10.Best estimate of 51 × 18? (a) 10000 (b) 1000 (c) 100
  11. 11.Best estimate of 38 × 86? (a) 3600 (b) 360 (c) 36000
  12. 12.Best estimate of 291 + 154? (a) 500 (b) 700 (c) 300
  13. 13.Best estimate of 22 × 21? (a) 40 (b) 400 (c) 4000
  14. 14.Best estimate of 97 × 12? (a) 10000 (b) 1000 (c) 100
  15. 15.Best estimate of 515 + 727? (a) 1200 (b) 1400 (c) 1000
  16. 16.Best estimate of 76 × 26? (a) 240 (b) 2400 (c) 24000
  17. 17.Best estimate of 49 × 89? (a) 450 (b) 45000 (c) 4500
  18. 18.Best estimate of 36 × 69? (a) 28000 (b) 2800 (c) 280
  19. 19.Best estimate of 67 × 30? (a) 21000 (b) 210 (c) 2100
  20. 20.Best estimate of 270 + 799? (a) 900 (b) 1100 (c) 1300
  21. 21.Best estimate of 82 × 76? (a) 64000 (b) 640 (c) 6400
  22. 22.Best estimate of 137 + 442? (a) 500 (b) 300 (c) 700
  23. 23.Best estimate of 441 + 699? (a) 1300 (b) 1100 (c) 900
  24. 24.Best estimate of 576 + 294? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 54 × 86? (a) 4500 (b) 450 (c) 45000
  26. 26.Best estimate of 382 + 398? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 27 × 76? (a) 240 (b) 2400 (c) 24000
  28. 28.Best estimate of 58 × 57? (a) 36000 (b) 360 (c) 3600
  29. 29.Best estimate of 188 + 135? (a) 100 (b) 300 (c) 500
  30. 30.Best estimate of 92 × 22? (a) 180 (b) 18000 (c) 1800
  31. 31.Best estimate of 58 × 19? (a) 12000 (b) 1200 (c) 120
  32. 32.Best estimate of 34 × 83? (a) 2400 (b) 240 (c) 24000
  33. 33.Best estimate of 316 + 783? (a) 1100 (b) 900 (c) 1300
  34. 34.Best estimate of 87 × 90? (a) 8100 (b) 81000 (c) 810
  35. 35.Best estimate of 638 + 121? (a) 900 (b) 500 (c) 700
  36. 36.Best estimate of 248 + 212? (a) 600 (b) 200 (c) 400
  37. 37.Best estimate of 827 + 777? (a) 1400 (b) 1800 (c) 1600
  38. 38.Best estimate of 22 × 84? (a) 16000 (b) 1600 (c) 160
  39. 39.Best estimate of 479 + 316? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 762 + 785? (a) 1600 (b) 1800 (c) 1400

Answer key

  1. 1200
  2. 3500
  3. 2500
  4. 7200
  5. 5600
  6. 2400
  7. 1100
  8. 1200
  9. 1100
  10. 1000
  11. 3600
  12. 500
  13. 400
  14. 1000
  15. 1200
  16. 2400
  17. 4500
  18. 2800
  19. 2100
  20. 1100
  21. 6400
  22. 500
  23. 1100
  24. 900
  25. 4500
  26. 800
  27. 2400
  28. 3600
  29. 300
  30. 1800
  31. 1200
  32. 2400
  33. 1100
  34. 8100
  35. 700
  36. 400
  37. 1600
  38. 1600
  39. 800
  40. 1600

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