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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 331 · 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 × 44? (a) 400 (b) 40 (c) 4000
  2. 2.Best estimate of 375 + 123? (a) 300 (b) 700 (c) 500
  3. 3.Best estimate of 19 × 73? (a) 14000 (b) 1400 (c) 140
  4. 4.Best estimate of 368 + 531? (a) 700 (b) 900 (c) 1100
  5. 5.Best estimate of 704 + 741? (a) 1600 (b) 1200 (c) 1400
  6. 6.Best estimate of 16 × 37? (a) 800 (b) 8000 (c) 80
  7. 7.Best estimate of 98 × 17? (a) 200 (b) 20000 (c) 2000
  8. 8.Best estimate of 160 + 219? (a) 600 (b) 200 (c) 400
  9. 9.Best estimate of 63 × 67? (a) 4200 (b) 420 (c) 42000
  10. 10.Best estimate of 327 + 261? (a) 600 (b) 400 (c) 800
  11. 11.Best estimate of 480 + 372? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 161 + 148? (a) 300 (b) 100 (c) 500
  13. 13.Best estimate of 76 × 26? (a) 2400 (b) 24000 (c) 240
  14. 14.Best estimate of 719 + 864? (a) 1600 (b) 1800 (c) 1400
  15. 15.Best estimate of 872 + 470? (a) 1400 (b) 1200 (c) 1600
  16. 16.Best estimate of 732 + 480? (a) 1400 (b) 1000 (c) 1200
  17. 17.Best estimate of 30 × 82? (a) 24000 (b) 2400 (c) 240
  18. 18.Best estimate of 201 + 484? (a) 700 (b) 500 (c) 900
  19. 19.Best estimate of 66 × 71? (a) 4900 (b) 49000 (c) 490
  20. 20.Best estimate of 494 + 551? (a) 900 (b) 1100 (c) 1300
  21. 21.Best estimate of 597 + 591? (a) 1000 (b) 1200 (c) 1400
  22. 22.Best estimate of 69 × 30? (a) 210 (b) 2100 (c) 21000
  23. 23.Best estimate of 824 + 834? (a) 1600 (b) 1800 (c) 1400
  24. 24.Best estimate of 72 × 60? (a) 420 (b) 4200 (c) 42000
  25. 25.Best estimate of 76 × 56? (a) 4800 (b) 48000 (c) 480
  26. 26.Best estimate of 410 + 752? (a) 1400 (b) 1000 (c) 1200
  27. 27.Best estimate of 89 × 66? (a) 6300 (b) 63000 (c) 630
  28. 28.Best estimate of 212 + 869? (a) 1300 (b) 900 (c) 1100
  29. 29.Best estimate of 38 × 13? (a) 4000 (b) 400 (c) 40
  30. 30.Best estimate of 64 × 82? (a) 48000 (b) 480 (c) 4800
  31. 31.Best estimate of 87 × 32? (a) 2700 (b) 270 (c) 27000
  32. 32.Best estimate of 447 + 437? (a) 600 (b) 800 (c) 1000
  33. 33.Best estimate of 460 + 696? (a) 1000 (b) 1400 (c) 1200
  34. 34.Best estimate of 46 × 66? (a) 350 (b) 35000 (c) 3500
  35. 35.Best estimate of 840 + 526? (a) 1100 (b) 1500 (c) 1300
  36. 36.Best estimate of 68 × 28? (a) 21000 (b) 2100 (c) 210
  37. 37.Best estimate of 20 × 71? (a) 1400 (b) 14000 (c) 140
  38. 38.Best estimate of 54 × 98? (a) 5000 (b) 500 (c) 50000
  39. 39.Best estimate of 70 × 96? (a) 7000 (b) 700 (c) 70000
  40. 40.Best estimate of 701 + 535? (a) 1400 (b) 1200 (c) 1000

Answer key

  1. 400
  2. 500
  3. 1400
  4. 900
  5. 1400
  6. 800
  7. 2000
  8. 400
  9. 4200
  10. 600
  11. 900
  12. 300
  13. 2400
  14. 1600
  15. 1400
  16. 1200
  17. 2400
  18. 700
  19. 4900
  20. 1100
  21. 1200
  22. 2100
  23. 1600
  24. 4200
  25. 4800
  26. 1200
  27. 6300
  28. 1100
  29. 400
  30. 4800
  31. 2700
  32. 800
  33. 1200
  34. 3500
  35. 1300
  36. 2100
  37. 1400
  38. 5000
  39. 7000
  40. 1200

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