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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 75 · 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 32 × 30? (a) 90 (b) 900 (c) 9000
  2. 2.Best estimate of 27 × 86? (a) 27000 (b) 270 (c) 2700
  3. 3.Best estimate of 66 × 63? (a) 420 (b) 4200 (c) 42000
  4. 4.Best estimate of 53 × 50? (a) 250 (b) 25000 (c) 2500
  5. 5.Best estimate of 158 + 397? (a) 800 (b) 400 (c) 600
  6. 6.Best estimate of 186 + 201? (a) 200 (b) 600 (c) 400
  7. 7.Best estimate of 59 × 33? (a) 180 (b) 18000 (c) 1800
  8. 8.Best estimate of 437 + 294? (a) 700 (b) 500 (c) 900
  9. 9.Best estimate of 42 × 27? (a) 120 (b) 1200 (c) 12000
  10. 10.Best estimate of 137 + 477? (a) 600 (b) 400 (c) 800
  11. 11.Best estimate of 44 × 50? (a) 200 (b) 2000 (c) 20000
  12. 12.Best estimate of 50 × 62? (a) 300 (b) 30000 (c) 3000
  13. 13.Best estimate of 701 + 707? (a) 1400 (b) 1600 (c) 1200
  14. 14.Best estimate of 519 + 259? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 576 + 419? (a) 1200 (b) 800 (c) 1000
  16. 16.Best estimate of 67 × 66? (a) 490 (b) 4900 (c) 49000
  17. 17.Best estimate of 28 × 63? (a) 18000 (b) 1800 (c) 180
  18. 18.Best estimate of 91 × 36? (a) 36000 (b) 3600 (c) 360
  19. 19.Best estimate of 629 + 691? (a) 1300 (b) 1500 (c) 1100
  20. 20.Best estimate of 704 + 484? (a) 1000 (b) 1200 (c) 1400
  21. 21.Best estimate of 71 × 83? (a) 560 (b) 5600 (c) 56000
  22. 22.Best estimate of 13 × 97? (a) 100 (b) 10000 (c) 1000
  23. 23.Best estimate of 44 × 33? (a) 120 (b) 12000 (c) 1200
  24. 24.Best estimate of 61 × 53? (a) 30000 (b) 300 (c) 3000
  25. 25.Best estimate of 51 × 76? (a) 400 (b) 40000 (c) 4000
  26. 26.Best estimate of 51 × 78? (a) 40000 (b) 4000 (c) 400
  27. 27.Best estimate of 26 × 29? (a) 900 (b) 90 (c) 9000
  28. 28.Best estimate of 14 × 67? (a) 700 (b) 70 (c) 7000
  29. 29.Best estimate of 512 + 734? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 77 × 49? (a) 40000 (b) 4000 (c) 400
  31. 31.Best estimate of 73 × 54? (a) 350 (b) 35000 (c) 3500
  32. 32.Best estimate of 200 + 355? (a) 400 (b) 800 (c) 600
  33. 33.Best estimate of 578 + 272? (a) 900 (b) 1100 (c) 700
  34. 34.Best estimate of 497 + 633? (a) 900 (b) 1100 (c) 1300
  35. 35.Best estimate of 451 + 829? (a) 1100 (b) 1300 (c) 1500
  36. 36.Best estimate of 62 × 63? (a) 360 (b) 3600 (c) 36000
  37. 37.Best estimate of 56 × 12? (a) 600 (b) 60 (c) 6000
  38. 38.Best estimate of 83 × 70? (a) 560 (b) 56000 (c) 5600
  39. 39.Best estimate of 218 + 452? (a) 700 (b) 900 (c) 500
  40. 40.Best estimate of 46 × 12? (a) 5000 (b) 500 (c) 50

Answer key

  1. 900
  2. 2700
  3. 4200
  4. 2500
  5. 600
  6. 400
  7. 1800
  8. 700
  9. 1200
  10. 600
  11. 2000
  12. 3000
  13. 1400
  14. 800
  15. 1000
  16. 4900
  17. 1800
  18. 3600
  19. 1300
  20. 1200
  21. 5600
  22. 1000
  23. 1200
  24. 3000
  25. 4000
  26. 4000
  27. 900
  28. 700
  29. 1200
  30. 4000
  31. 3500
  32. 600
  33. 900
  34. 1100
  35. 1300
  36. 3600
  37. 600
  38. 5600
  39. 700
  40. 500

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