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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 555 · 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 12 × 53? (a) 5000 (b) 50 (c) 500
  2. 2.Best estimate of 495 + 235? (a) 900 (b) 700 (c) 500
  3. 3.Best estimate of 84 × 49? (a) 40000 (b) 400 (c) 4000
  4. 4.Best estimate of 211 + 555? (a) 600 (b) 1000 (c) 800
  5. 5.Best estimate of 141 + 719? (a) 1000 (b) 800 (c) 600
  6. 6.Best estimate of 19 × 50? (a) 10000 (b) 100 (c) 1000
  7. 7.Best estimate of 33 × 86? (a) 2700 (b) 270 (c) 27000
  8. 8.Best estimate of 72 × 39? (a) 280 (b) 2800 (c) 28000
  9. 9.Best estimate of 134 + 320? (a) 400 (b) 200 (c) 600
  10. 10.Best estimate of 68 × 73? (a) 49000 (b) 4900 (c) 490
  11. 11.Best estimate of 67 × 71? (a) 4900 (b) 490 (c) 49000
  12. 12.Best estimate of 257 + 142? (a) 200 (b) 400 (c) 600
  13. 13.Best estimate of 81 × 68? (a) 5600 (b) 56000 (c) 560
  14. 14.Best estimate of 556 + 470? (a) 1100 (b) 900 (c) 1300
  15. 15.Best estimate of 561 + 193? (a) 800 (b) 1000 (c) 600
  16. 16.Best estimate of 796 + 835? (a) 1600 (b) 1800 (c) 1400
  17. 17.Best estimate of 32 × 46? (a) 1500 (b) 15000 (c) 150
  18. 18.Best estimate of 96 × 46? (a) 50000 (b) 5000 (c) 500
  19. 19.Best estimate of 537 + 630? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 39 × 37? (a) 16000 (b) 160 (c) 1600
  21. 21.Best estimate of 707 + 207? (a) 1100 (b) 900 (c) 700
  22. 22.Best estimate of 290 + 209? (a) 500 (b) 300 (c) 700
  23. 23.Best estimate of 540 + 790? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 83 × 96? (a) 8000 (b) 800 (c) 80000
  25. 25.Best estimate of 28 × 17? (a) 600 (b) 60 (c) 6000
  26. 26.Best estimate of 328 + 714? (a) 1200 (b) 800 (c) 1000
  27. 27.Best estimate of 371 + 379? (a) 1000 (b) 600 (c) 800
  28. 28.Best estimate of 527 + 234? (a) 900 (b) 500 (c) 700
  29. 29.Best estimate of 97 × 84? (a) 8000 (b) 800 (c) 80000
  30. 30.Best estimate of 58 × 60? (a) 36000 (b) 360 (c) 3600
  31. 31.Best estimate of 47 × 12? (a) 50 (b) 5000 (c) 500
  32. 32.Best estimate of 54 × 61? (a) 3000 (b) 30000 (c) 300
  33. 33.Best estimate of 424 + 151? (a) 600 (b) 800 (c) 400
  34. 34.Best estimate of 23 × 70? (a) 14000 (b) 1400 (c) 140
  35. 35.Best estimate of 48 × 49? (a) 25000 (b) 250 (c) 2500
  36. 36.Best estimate of 91 × 49? (a) 4500 (b) 45000 (c) 450
  37. 37.Best estimate of 184 + 863? (a) 1100 (b) 900 (c) 1300
  38. 38.Best estimate of 34 × 41? (a) 12000 (b) 120 (c) 1200
  39. 39.Best estimate of 469 + 121? (a) 800 (b) 400 (c) 600
  40. 40.Best estimate of 26 × 16? (a) 6000 (b) 60 (c) 600

Answer key

  1. 500
  2. 700
  3. 4000
  4. 800
  5. 800
  6. 1000
  7. 2700
  8. 2800
  9. 400
  10. 4900
  11. 4900
  12. 400
  13. 5600
  14. 1100
  15. 800
  16. 1600
  17. 1500
  18. 5000
  19. 1100
  20. 1600
  21. 900
  22. 500
  23. 1300
  24. 8000
  25. 600
  26. 1000
  27. 800
  28. 700
  29. 8000
  30. 3600
  31. 500
  32. 3000
  33. 600
  34. 1400
  35. 2500
  36. 4500
  37. 1100
  38. 1200
  39. 600
  40. 600

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