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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 849 · 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 90 × 82? (a) 7200 (b) 72000 (c) 720
  2. 2.Best estimate of 598 + 474? (a) 1100 (b) 900 (c) 1300
  3. 3.Best estimate of 559 + 830? (a) 1200 (b) 1600 (c) 1400
  4. 4.Best estimate of 16 × 43? (a) 8000 (b) 80 (c) 800
  5. 5.Best estimate of 76 × 17? (a) 16000 (b) 1600 (c) 160
  6. 6.Best estimate of 30 × 30? (a) 90 (b) 900 (c) 9000
  7. 7.Best estimate of 88 × 32? (a) 270 (b) 27000 (c) 2700
  8. 8.Best estimate of 663 + 288? (a) 1200 (b) 1000 (c) 800
  9. 9.Best estimate of 633 + 469? (a) 1100 (b) 1300 (c) 900
  10. 10.Best estimate of 16 × 93? (a) 18000 (b) 180 (c) 1800
  11. 11.Best estimate of 96 × 23? (a) 20000 (b) 200 (c) 2000
  12. 12.Best estimate of 464 + 813? (a) 1500 (b) 1100 (c) 1300
  13. 13.Best estimate of 23 × 32? (a) 600 (b) 60 (c) 6000
  14. 14.Best estimate of 39 × 18? (a) 800 (b) 8000 (c) 80
  15. 15.Best estimate of 343 + 854? (a) 1400 (b) 1000 (c) 1200
  16. 16.Best estimate of 137 + 495? (a) 800 (b) 400 (c) 600
  17. 17.Best estimate of 473 + 801? (a) 1500 (b) 1100 (c) 1300
  18. 18.Best estimate of 294 + 482? (a) 800 (b) 600 (c) 1000
  19. 19.Best estimate of 50 × 56? (a) 30000 (b) 300 (c) 3000
  20. 20.Best estimate of 36 × 93? (a) 360 (b) 3600 (c) 36000
  21. 21.Best estimate of 765 + 488? (a) 1500 (b) 1300 (c) 1100
  22. 22.Best estimate of 16 × 63? (a) 12000 (b) 120 (c) 1200
  23. 23.Best estimate of 52 × 54? (a) 25000 (b) 250 (c) 2500
  24. 24.Best estimate of 860 + 376? (a) 1100 (b) 1500 (c) 1300
  25. 25.Best estimate of 32 × 36? (a) 1200 (b) 120 (c) 12000
  26. 26.Best estimate of 71 × 80? (a) 560 (b) 56000 (c) 5600
  27. 27.Best estimate of 13 × 83? (a) 8000 (b) 80 (c) 800
  28. 28.Best estimate of 50 × 82? (a) 400 (b) 4000 (c) 40000
  29. 29.Best estimate of 438 + 181? (a) 800 (b) 600 (c) 400
  30. 30.Best estimate of 498 + 482? (a) 1000 (b) 800 (c) 1200
  31. 31.Best estimate of 21 × 49? (a) 1000 (b) 10000 (c) 100
  32. 32.Best estimate of 19 × 66? (a) 14000 (b) 1400 (c) 140
  33. 33.Best estimate of 96 × 53? (a) 500 (b) 50000 (c) 5000
  34. 34.Best estimate of 262 + 124? (a) 200 (b) 600 (c) 400
  35. 35.Best estimate of 67 × 69? (a) 4900 (b) 49000 (c) 490
  36. 36.Best estimate of 298 + 311? (a) 800 (b) 600 (c) 400
  37. 37.Best estimate of 36 × 14? (a) 400 (b) 4000 (c) 40
  38. 38.Best estimate of 30 × 64? (a) 180 (b) 1800 (c) 18000
  39. 39.Best estimate of 152 + 327? (a) 700 (b) 300 (c) 500
  40. 40.Best estimate of 62 × 31? (a) 180 (b) 18000 (c) 1800

Answer key

  1. 7200
  2. 1100
  3. 1400
  4. 800
  5. 1600
  6. 900
  7. 2700
  8. 1000
  9. 1100
  10. 1800
  11. 2000
  12. 1300
  13. 600
  14. 800
  15. 1200
  16. 600
  17. 1300
  18. 800
  19. 3000
  20. 3600
  21. 1300
  22. 1200
  23. 2500
  24. 1300
  25. 1200
  26. 5600
  27. 800
  28. 4000
  29. 600
  30. 1000
  31. 1000
  32. 1400
  33. 5000
  34. 400
  35. 4900
  36. 600
  37. 400
  38. 1800
  39. 500
  40. 1800

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