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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 274 · 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 648 + 313? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 49 × 94? (a) 450 (b) 4500 (c) 45000
  3. 3.Best estimate of 386 + 798? (a) 1200 (b) 1000 (c) 1400
  4. 4.Best estimate of 77 × 12? (a) 80 (b) 8000 (c) 800
  5. 5.Best estimate of 815 + 530? (a) 1500 (b) 1100 (c) 1300
  6. 6.Best estimate of 86 × 39? (a) 3600 (b) 36000 (c) 360
  7. 7.Best estimate of 795 + 439? (a) 1000 (b) 1400 (c) 1200
  8. 8.Best estimate of 56 × 76? (a) 480 (b) 48000 (c) 4800
  9. 9.Best estimate of 409 + 658? (a) 1100 (b) 900 (c) 1300
  10. 10.Best estimate of 195 + 302? (a) 700 (b) 500 (c) 300
  11. 11.Best estimate of 62 × 92? (a) 5400 (b) 54000 (c) 540
  12. 12.Best estimate of 810 + 651? (a) 1700 (b) 1500 (c) 1300
  13. 13.Best estimate of 73 × 46? (a) 3500 (b) 35000 (c) 350
  14. 14.Best estimate of 26 × 56? (a) 1800 (b) 18000 (c) 180
  15. 15.Best estimate of 60 × 26? (a) 18000 (b) 1800 (c) 180
  16. 16.Best estimate of 733 + 680? (a) 1200 (b) 1600 (c) 1400
  17. 17.Best estimate of 16 × 84? (a) 16000 (b) 1600 (c) 160
  18. 18.Best estimate of 58 × 86? (a) 540 (b) 54000 (c) 5400
  19. 19.Best estimate of 42 × 56? (a) 2400 (b) 24000 (c) 240
  20. 20.Best estimate of 14 × 44? (a) 4000 (b) 40 (c) 400
  21. 21.Best estimate of 52 × 16? (a) 10000 (b) 1000 (c) 100
  22. 22.Best estimate of 278 + 490? (a) 600 (b) 800 (c) 1000
  23. 23.Best estimate of 38 × 30? (a) 12000 (b) 120 (c) 1200
  24. 24.Best estimate of 123 + 693? (a) 1000 (b) 600 (c) 800
  25. 25.Best estimate of 58 × 48? (a) 300 (b) 30000 (c) 3000
  26. 26.Best estimate of 36 × 51? (a) 20000 (b) 2000 (c) 200
  27. 27.Best estimate of 93 × 78? (a) 72000 (b) 720 (c) 7200
  28. 28.Best estimate of 146 + 434? (a) 300 (b) 700 (c) 500
  29. 29.Best estimate of 58 × 33? (a) 180 (b) 18000 (c) 1800
  30. 30.Best estimate of 789 + 325? (a) 1300 (b) 1100 (c) 900
  31. 31.Best estimate of 620 + 799? (a) 1400 (b) 1200 (c) 1600
  32. 32.Best estimate of 714 + 661? (a) 1200 (b) 1400 (c) 1600
  33. 33.Best estimate of 51 × 96? (a) 500 (b) 50000 (c) 5000
  34. 34.Best estimate of 305 + 122? (a) 600 (b) 200 (c) 400
  35. 35.Best estimate of 800 + 732? (a) 1500 (b) 1300 (c) 1700
  36. 36.Best estimate of 869 + 820? (a) 1900 (b) 1500 (c) 1700
  37. 37.Best estimate of 84 × 86? (a) 72000 (b) 720 (c) 7200
  38. 38.Best estimate of 13 × 94? (a) 9000 (b) 90 (c) 900
  39. 39.Best estimate of 27 × 46? (a) 1500 (b) 15000 (c) 150
  40. 40.Best estimate of 69 × 59? (a) 42000 (b) 4200 (c) 420

Answer key

  1. 900
  2. 4500
  3. 1200
  4. 800
  5. 1300
  6. 3600
  7. 1200
  8. 4800
  9. 1100
  10. 500
  11. 5400
  12. 1500
  13. 3500
  14. 1800
  15. 1800
  16. 1400
  17. 1600
  18. 5400
  19. 2400
  20. 400
  21. 1000
  22. 800
  23. 1200
  24. 800
  25. 3000
  26. 2000
  27. 7200
  28. 500
  29. 1800
  30. 1100
  31. 1400
  32. 1400
  33. 5000
  34. 400
  35. 1500
  36. 1700
  37. 7200
  38. 900
  39. 1500
  40. 4200

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