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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 229 · 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 86 × 20? (a) 180 (b) 1800 (c) 18000
  2. 2.Best estimate of 670 + 319? (a) 800 (b) 1000 (c) 1200
  3. 3.Best estimate of 42 × 68? (a) 2800 (b) 280 (c) 28000
  4. 4.Best estimate of 47 × 74? (a) 35000 (b) 350 (c) 3500
  5. 5.Best estimate of 711 + 453? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 19 × 23? (a) 40 (b) 4000 (c) 400
  7. 7.Best estimate of 49 × 67? (a) 3500 (b) 35000 (c) 350
  8. 8.Best estimate of 216 + 159? (a) 600 (b) 400 (c) 200
  9. 9.Best estimate of 368 + 668? (a) 1300 (b) 1100 (c) 900
  10. 10.Best estimate of 403 + 413? (a) 1000 (b) 800 (c) 600
  11. 11.Best estimate of 70 × 83? (a) 56000 (b) 5600 (c) 560
  12. 12.Best estimate of 57 × 34? (a) 180 (b) 18000 (c) 1800
  13. 13.Best estimate of 232 + 516? (a) 900 (b) 500 (c) 700
  14. 14.Best estimate of 27 × 79? (a) 2400 (b) 24000 (c) 240
  15. 15.Best estimate of 371 + 234? (a) 800 (b) 600 (c) 400
  16. 16.Best estimate of 94 × 26? (a) 2700 (b) 27000 (c) 270
  17. 17.Best estimate of 28 × 76? (a) 240 (b) 24000 (c) 2400
  18. 18.Best estimate of 31 × 92? (a) 2700 (b) 270 (c) 27000
  19. 19.Best estimate of 202 + 185? (a) 600 (b) 200 (c) 400
  20. 20.Best estimate of 68 × 96? (a) 70000 (b) 700 (c) 7000
  21. 21.Best estimate of 92 × 97? (a) 900 (b) 9000 (c) 90000
  22. 22.Best estimate of 323 + 580? (a) 1100 (b) 700 (c) 900
  23. 23.Best estimate of 18 × 19? (a) 4000 (b) 400 (c) 40
  24. 24.Best estimate of 62 × 18? (a) 12000 (b) 120 (c) 1200
  25. 25.Best estimate of 23 × 56? (a) 120 (b) 1200 (c) 12000
  26. 26.Best estimate of 227 + 875? (a) 1300 (b) 900 (c) 1100
  27. 27.Best estimate of 414 + 647? (a) 1000 (b) 1200 (c) 800
  28. 28.Best estimate of 56 × 12? (a) 600 (b) 6000 (c) 60
  29. 29.Best estimate of 338 + 863? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 64 × 44? (a) 24000 (b) 2400 (c) 240
  31. 31.Best estimate of 42 × 36? (a) 160 (b) 1600 (c) 16000
  32. 32.Best estimate of 78 × 63? (a) 480 (b) 48000 (c) 4800
  33. 33.Best estimate of 216 + 670? (a) 900 (b) 700 (c) 1100
  34. 34.Best estimate of 72 × 60? (a) 42000 (b) 420 (c) 4200
  35. 35.Best estimate of 861 + 541? (a) 1600 (b) 1200 (c) 1400
  36. 36.Best estimate of 90 × 23? (a) 1800 (b) 180 (c) 18000
  37. 37.Best estimate of 51 × 93? (a) 45000 (b) 4500 (c) 450
  38. 38.Best estimate of 86 × 82? (a) 72000 (b) 7200 (c) 720
  39. 39.Best estimate of 579 + 618? (a) 1400 (b) 1200 (c) 1000
  40. 40.Best estimate of 665 + 382? (a) 1100 (b) 900 (c) 1300

Answer key

  1. 1800
  2. 1000
  3. 2800
  4. 3500
  5. 1200
  6. 400
  7. 3500
  8. 400
  9. 1100
  10. 800
  11. 5600
  12. 1800
  13. 700
  14. 2400
  15. 600
  16. 2700
  17. 2400
  18. 2700
  19. 400
  20. 7000
  21. 9000
  22. 900
  23. 400
  24. 1200
  25. 1200
  26. 1100
  27. 1000
  28. 600
  29. 1200
  30. 2400
  31. 1600
  32. 4800
  33. 900
  34. 4200
  35. 1400
  36. 1800
  37. 4500
  38. 7200
  39. 1200
  40. 1100

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