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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 648 · 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 87 × 27? (a) 2700 (b) 270 (c) 27000
  2. 2.Best estimate of 12 × 94? (a) 900 (b) 9000 (c) 90
  3. 3.Best estimate of 841 + 436? (a) 1200 (b) 1400 (c) 1000
  4. 4.Best estimate of 31 × 43? (a) 12000 (b) 120 (c) 1200
  5. 5.Best estimate of 458 + 669? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 49 × 13? (a) 5000 (b) 50 (c) 500
  7. 7.Best estimate of 815 + 397? (a) 1400 (b) 1200 (c) 1000
  8. 8.Best estimate of 42 × 96? (a) 40000 (b) 4000 (c) 400
  9. 9.Best estimate of 375 + 532? (a) 900 (b) 700 (c) 1100
  10. 10.Best estimate of 733 + 264? (a) 1000 (b) 1200 (c) 800
  11. 11.Best estimate of 18 × 39? (a) 80 (b) 800 (c) 8000
  12. 12.Best estimate of 64 × 92? (a) 54000 (b) 540 (c) 5400
  13. 13.Best estimate of 77 × 17? (a) 160 (b) 16000 (c) 1600
  14. 14.Best estimate of 49 × 32? (a) 1500 (b) 15000 (c) 150
  15. 15.Best estimate of 519 + 851? (a) 1400 (b) 1200 (c) 1600
  16. 16.Best estimate of 40 × 13? (a) 4000 (b) 400 (c) 40
  17. 17.Best estimate of 69 × 20? (a) 140 (b) 14000 (c) 1400
  18. 18.Best estimate of 70 × 38? (a) 2800 (b) 28000 (c) 280
  19. 19.Best estimate of 16 × 92? (a) 1800 (b) 18000 (c) 180
  20. 20.Best estimate of 81 × 73? (a) 560 (b) 5600 (c) 56000
  21. 21.Best estimate of 177 + 211? (a) 600 (b) 200 (c) 400
  22. 22.Best estimate of 759 + 720? (a) 1500 (b) 1700 (c) 1300
  23. 23.Best estimate of 503 + 543? (a) 1200 (b) 800 (c) 1000
  24. 24.Best estimate of 78 × 56? (a) 4800 (b) 48000 (c) 480
  25. 25.Best estimate of 61 × 47? (a) 300 (b) 3000 (c) 30000
  26. 26.Best estimate of 803 + 735? (a) 1700 (b) 1300 (c) 1500
  27. 27.Best estimate of 30 × 67? (a) 21000 (b) 210 (c) 2100
  28. 28.Best estimate of 41 × 86? (a) 36000 (b) 3600 (c) 360
  29. 29.Best estimate of 507 + 731? (a) 1000 (b) 1400 (c) 1200
  30. 30.Best estimate of 90 × 26? (a) 2700 (b) 27000 (c) 270
  31. 31.Best estimate of 210 + 394? (a) 600 (b) 400 (c) 800
  32. 32.Best estimate of 18 × 96? (a) 20000 (b) 200 (c) 2000
  33. 33.Best estimate of 633 + 448? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 78 × 46? (a) 4000 (b) 40000 (c) 400
  35. 35.Best estimate of 40 × 94? (a) 3600 (b) 360 (c) 36000
  36. 36.Best estimate of 41 × 51? (a) 200 (b) 2000 (c) 20000
  37. 37.Best estimate of 521 + 132? (a) 600 (b) 800 (c) 400
  38. 38.Best estimate of 346 + 746? (a) 1200 (b) 1000 (c) 800
  39. 39.Best estimate of 161 + 466? (a) 500 (b) 700 (c) 900
  40. 40.Best estimate of 542 + 860? (a) 1400 (b) 1200 (c) 1600

Answer key

  1. 2700
  2. 900
  3. 1200
  4. 1200
  5. 1200
  6. 500
  7. 1200
  8. 4000
  9. 900
  10. 1000
  11. 800
  12. 5400
  13. 1600
  14. 1500
  15. 1400
  16. 400
  17. 1400
  18. 2800
  19. 1800
  20. 5600
  21. 400
  22. 1500
  23. 1000
  24. 4800
  25. 3000
  26. 1500
  27. 2100
  28. 3600
  29. 1200
  30. 2700
  31. 600
  32. 2000
  33. 1000
  34. 4000
  35. 3600
  36. 2000
  37. 600
  38. 1000
  39. 700
  40. 1400

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