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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 253 · 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 23 × 31? (a) 60 (b) 600 (c) 6000
  2. 2.Best estimate of 388 + 612? (a) 1000 (b) 1200 (c) 800
  3. 3.Best estimate of 43 × 30? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 126 + 443? (a) 300 (b) 500 (c) 700
  5. 5.Best estimate of 777 + 392? (a) 1200 (b) 1400 (c) 1000
  6. 6.Best estimate of 218 + 156? (a) 600 (b) 200 (c) 400
  7. 7.Best estimate of 16 × 63? (a) 12000 (b) 120 (c) 1200
  8. 8.Best estimate of 94 × 42? (a) 3600 (b) 360 (c) 36000
  9. 9.Best estimate of 219 + 362? (a) 600 (b) 400 (c) 800
  10. 10.Best estimate of 719 + 220? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 16 × 37? (a) 800 (b) 80 (c) 8000
  12. 12.Best estimate of 21 × 34? (a) 600 (b) 60 (c) 6000
  13. 13.Best estimate of 76 × 64? (a) 48000 (b) 480 (c) 4800
  14. 14.Best estimate of 93 × 41? (a) 3600 (b) 36000 (c) 360
  15. 15.Best estimate of 331 + 615? (a) 1100 (b) 700 (c) 900
  16. 16.Best estimate of 12 × 83? (a) 800 (b) 80 (c) 8000
  17. 17.Best estimate of 184 + 170? (a) 400 (b) 200 (c) 600
  18. 18.Best estimate of 40 × 47? (a) 20000 (b) 200 (c) 2000
  19. 19.Best estimate of 872 + 747? (a) 1800 (b) 1400 (c) 1600
  20. 20.Best estimate of 494 + 630? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 60 × 48? (a) 30000 (b) 300 (c) 3000
  22. 22.Best estimate of 728 + 281? (a) 800 (b) 1000 (c) 1200
  23. 23.Best estimate of 67 × 81? (a) 5600 (b) 56000 (c) 560
  24. 24.Best estimate of 17 × 69? (a) 140 (b) 1400 (c) 14000
  25. 25.Best estimate of 783 + 529? (a) 1100 (b) 1500 (c) 1300
  26. 26.Best estimate of 41 × 36? (a) 1600 (b) 16000 (c) 160
  27. 27.Best estimate of 22 × 76? (a) 1600 (b) 16000 (c) 160
  28. 28.Best estimate of 74 × 68? (a) 490 (b) 4900 (c) 49000
  29. 29.Best estimate of 18 × 32? (a) 600 (b) 60 (c) 6000
  30. 30.Best estimate of 54 × 28? (a) 15000 (b) 150 (c) 1500
  31. 31.Best estimate of 92 × 57? (a) 540 (b) 5400 (c) 54000
  32. 32.Best estimate of 50 × 42? (a) 20000 (b) 2000 (c) 200
  33. 33.Best estimate of 17 × 97? (a) 200 (b) 20000 (c) 2000
  34. 34.Best estimate of 320 + 148? (a) 600 (b) 200 (c) 400
  35. 35.Best estimate of 36 × 73? (a) 28000 (b) 2800 (c) 280
  36. 36.Best estimate of 18 × 88? (a) 1800 (b) 18000 (c) 180
  37. 37.Best estimate of 54 × 78? (a) 40000 (b) 4000 (c) 400
  38. 38.Best estimate of 34 × 36? (a) 12000 (b) 1200 (c) 120
  39. 39.Best estimate of 66 × 63? (a) 42000 (b) 420 (c) 4200
  40. 40.Best estimate of 58 × 57? (a) 36000 (b) 3600 (c) 360

Answer key

  1. 600
  2. 1000
  3. 1200
  4. 500
  5. 1200
  6. 400
  7. 1200
  8. 3600
  9. 600
  10. 900
  11. 800
  12. 600
  13. 4800
  14. 3600
  15. 900
  16. 800
  17. 400
  18. 2000
  19. 1600
  20. 1100
  21. 3000
  22. 1000
  23. 5600
  24. 1400
  25. 1300
  26. 1600
  27. 1600
  28. 4900
  29. 600
  30. 1500
  31. 5400
  32. 2000
  33. 2000
  34. 400
  35. 2800
  36. 1800
  37. 4000
  38. 1200
  39. 4200
  40. 3600

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