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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 397 · 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 43 × 98? (a) 400 (b) 4000 (c) 40000
  2. 2.Best estimate of 855 + 471? (a) 1400 (b) 1600 (c) 1200
  3. 3.Best estimate of 46 × 39? (a) 200 (b) 20000 (c) 2000
  4. 4.Best estimate of 879 + 775? (a) 1700 (b) 1900 (c) 1500
  5. 5.Best estimate of 711 + 488? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 92 × 57? (a) 5400 (b) 54000 (c) 540
  7. 7.Best estimate of 856 + 447? (a) 1500 (b) 1100 (c) 1300
  8. 8.Best estimate of 672 + 496? (a) 1200 (b) 1000 (c) 1400
  9. 9.Best estimate of 707 + 273? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 79 × 34? (a) 240 (b) 2400 (c) 24000
  11. 11.Best estimate of 86 × 78? (a) 720 (b) 7200 (c) 72000
  12. 12.Best estimate of 806 + 552? (a) 1600 (b) 1400 (c) 1200
  13. 13.Best estimate of 66 × 54? (a) 350 (b) 3500 (c) 35000
  14. 14.Best estimate of 96 × 80? (a) 8000 (b) 80000 (c) 800
  15. 15.Best estimate of 326 + 512? (a) 1000 (b) 800 (c) 600
  16. 16.Best estimate of 40 × 69? (a) 2800 (b) 28000 (c) 280
  17. 17.Best estimate of 66 × 59? (a) 42000 (b) 420 (c) 4200
  18. 18.Best estimate of 761 + 345? (a) 900 (b) 1100 (c) 1300
  19. 19.Best estimate of 698 + 260? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 872 + 256? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 763 + 322? (a) 1100 (b) 900 (c) 1300
  22. 22.Best estimate of 22 × 29? (a) 6000 (b) 600 (c) 60
  23. 23.Best estimate of 50 × 73? (a) 35000 (b) 3500 (c) 350
  24. 24.Best estimate of 769 + 485? (a) 1100 (b) 1300 (c) 1500
  25. 25.Best estimate of 375 + 810? (a) 1000 (b) 1400 (c) 1200
  26. 26.Best estimate of 19 × 70? (a) 14000 (b) 140 (c) 1400
  27. 27.Best estimate of 810 + 553? (a) 1200 (b) 1600 (c) 1400
  28. 28.Best estimate of 567 + 616? (a) 1000 (b) 1200 (c) 1400
  29. 29.Best estimate of 293 + 390? (a) 900 (b) 700 (c) 500
  30. 30.Best estimate of 12 × 18? (a) 200 (b) 20 (c) 2000
  31. 31.Best estimate of 815 + 751? (a) 1600 (b) 1400 (c) 1800
  32. 32.Best estimate of 16 × 68? (a) 1400 (b) 14000 (c) 140
  33. 33.Best estimate of 59 × 51? (a) 300 (b) 3000 (c) 30000
  34. 34.Best estimate of 64 × 22? (a) 1200 (b) 12000 (c) 120
  35. 35.Best estimate of 66 × 18? (a) 1400 (b) 140 (c) 14000
  36. 36.Best estimate of 28 × 38? (a) 12000 (b) 1200 (c) 120
  37. 37.Best estimate of 31 × 71? (a) 2100 (b) 21000 (c) 210
  38. 38.Best estimate of 628 + 800? (a) 1600 (b) 1400 (c) 1200
  39. 39.Best estimate of 190 + 411? (a) 600 (b) 400 (c) 800
  40. 40.Best estimate of 244 + 735? (a) 1100 (b) 900 (c) 700

Answer key

  1. 4000
  2. 1400
  3. 2000
  4. 1700
  5. 1200
  6. 5400
  7. 1300
  8. 1200
  9. 1000
  10. 2400
  11. 7200
  12. 1400
  13. 3500
  14. 8000
  15. 800
  16. 2800
  17. 4200
  18. 1100
  19. 1000
  20. 1200
  21. 1100
  22. 600
  23. 3500
  24. 1300
  25. 1200
  26. 1400
  27. 1400
  28. 1200
  29. 700
  30. 200
  31. 1600
  32. 1400
  33. 3000
  34. 1200
  35. 1400
  36. 1200
  37. 2100
  38. 1400
  39. 600
  40. 900

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