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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 949 · 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 34 × 58? (a) 180 (b) 18000 (c) 1800
  2. 2.Best estimate of 22 × 46? (a) 1000 (b) 10000 (c) 100
  3. 3.Best estimate of 68 × 71? (a) 490 (b) 49000 (c) 4900
  4. 4.Best estimate of 584 + 848? (a) 1600 (b) 1400 (c) 1200
  5. 5.Best estimate of 57 × 46? (a) 30000 (b) 3000 (c) 300
  6. 6.Best estimate of 58 × 48? (a) 300 (b) 30000 (c) 3000
  7. 7.Best estimate of 42 × 43? (a) 160 (b) 1600 (c) 16000
  8. 8.Best estimate of 86 × 78? (a) 72000 (b) 720 (c) 7200
  9. 9.Best estimate of 40 × 61? (a) 24000 (b) 240 (c) 2400
  10. 10.Best estimate of 89 × 19? (a) 18000 (b) 180 (c) 1800
  11. 11.Best estimate of 23 × 53? (a) 1000 (b) 10000 (c) 100
  12. 12.Best estimate of 728 + 808? (a) 1700 (b) 1500 (c) 1300
  13. 13.Best estimate of 97 × 98? (a) 1000 (b) 10000 (c) 100000
  14. 14.Best estimate of 78 × 51? (a) 40000 (b) 4000 (c) 400
  15. 15.Best estimate of 19 × 26? (a) 600 (b) 6000 (c) 60
  16. 16.Best estimate of 151 + 705? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 218 + 465? (a) 900 (b) 500 (c) 700
  18. 18.Best estimate of 214 + 548? (a) 900 (b) 500 (c) 700
  19. 19.Best estimate of 789 + 320? (a) 1100 (b) 1300 (c) 900
  20. 20.Best estimate of 41 × 34? (a) 120 (b) 12000 (c) 1200
  21. 21.Best estimate of 16 × 60? (a) 120 (b) 1200 (c) 12000
  22. 22.Best estimate of 31 × 76? (a) 2400 (b) 240 (c) 24000
  23. 23.Best estimate of 849 + 540? (a) 1100 (b) 1300 (c) 1500
  24. 24.Best estimate of 79 × 88? (a) 7200 (b) 720 (c) 72000
  25. 25.Best estimate of 76 × 63? (a) 48000 (b) 4800 (c) 480
  26. 26.Best estimate of 751 + 651? (a) 1500 (b) 1700 (c) 1300
  27. 27.Best estimate of 585 + 567? (a) 1000 (b) 1200 (c) 1400
  28. 28.Best estimate of 29 × 32? (a) 900 (b) 9000 (c) 90
  29. 29.Best estimate of 93 × 49? (a) 4500 (b) 45000 (c) 450
  30. 30.Best estimate of 62 × 18? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 53 × 59? (a) 3000 (b) 30000 (c) 300
  32. 32.Best estimate of 86 × 54? (a) 450 (b) 4500 (c) 45000
  33. 33.Best estimate of 66 × 30? (a) 210 (b) 21000 (c) 2100
  34. 34.Best estimate of 24 × 96? (a) 200 (b) 20000 (c) 2000
  35. 35.Best estimate of 687 + 555? (a) 1300 (b) 1100 (c) 1500
  36. 36.Best estimate of 81 × 61? (a) 4800 (b) 48000 (c) 480
  37. 37.Best estimate of 211 + 427? (a) 600 (b) 400 (c) 800
  38. 38.Best estimate of 88 × 54? (a) 4500 (b) 450 (c) 45000
  39. 39.Best estimate of 338 + 461? (a) 800 (b) 1000 (c) 600
  40. 40.Best estimate of 61 × 43? (a) 2400 (b) 24000 (c) 240

Answer key

  1. 1800
  2. 1000
  3. 4900
  4. 1400
  5. 3000
  6. 3000
  7. 1600
  8. 7200
  9. 2400
  10. 1800
  11. 1000
  12. 1500
  13. 10000
  14. 4000
  15. 600
  16. 900
  17. 700
  18. 700
  19. 1100
  20. 1200
  21. 1200
  22. 2400
  23. 1300
  24. 7200
  25. 4800
  26. 1500
  27. 1200
  28. 900
  29. 4500
  30. 1200
  31. 3000
  32. 4500
  33. 2100
  34. 2000
  35. 1300
  36. 4800
  37. 600
  38. 4500
  39. 800
  40. 2400

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