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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 53 · 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 509 + 773? (a) 1300 (b) 1500 (c) 1100
  2. 2.Best estimate of 176 + 321? (a) 300 (b) 500 (c) 700
  3. 3.Best estimate of 24 × 43? (a) 800 (b) 80 (c) 8000
  4. 4.Best estimate of 74 × 20? (a) 140 (b) 14000 (c) 1400
  5. 5.Best estimate of 745 + 235? (a) 1100 (b) 700 (c) 900
  6. 6.Best estimate of 58 × 36? (a) 240 (b) 24000 (c) 2400
  7. 7.Best estimate of 776 + 639? (a) 1200 (b) 1600 (c) 1400
  8. 8.Best estimate of 870 + 502? (a) 1400 (b) 1200 (c) 1600
  9. 9.Best estimate of 86 × 14? (a) 900 (b) 90 (c) 9000
  10. 10.Best estimate of 879 + 232? (a) 1300 (b) 900 (c) 1100
  11. 11.Best estimate of 794 + 471? (a) 1500 (b) 1300 (c) 1100
  12. 12.Best estimate of 260 + 253? (a) 600 (b) 800 (c) 400
  13. 13.Best estimate of 63 × 66? (a) 420 (b) 42000 (c) 4200
  14. 14.Best estimate of 20 × 31? (a) 600 (b) 6000 (c) 60
  15. 15.Best estimate of 719 + 740? (a) 1400 (b) 1200 (c) 1600
  16. 16.Best estimate of 575 + 822? (a) 1400 (b) 1200 (c) 1600
  17. 17.Best estimate of 146 + 532? (a) 600 (b) 400 (c) 800
  18. 18.Best estimate of 22 × 66? (a) 1400 (b) 140 (c) 14000
  19. 19.Best estimate of 24 × 41? (a) 800 (b) 8000 (c) 80
  20. 20.Best estimate of 266 + 880? (a) 1200 (b) 1000 (c) 1400
  21. 21.Best estimate of 188 + 634? (a) 600 (b) 1000 (c) 800
  22. 22.Best estimate of 749 + 512? (a) 1000 (b) 1400 (c) 1200
  23. 23.Best estimate of 16 × 78? (a) 160 (b) 1600 (c) 16000
  24. 24.Best estimate of 88 × 62? (a) 54000 (b) 540 (c) 5400
  25. 25.Best estimate of 66 × 57? (a) 420 (b) 4200 (c) 42000
  26. 26.Best estimate of 56 × 63? (a) 3600 (b) 36000 (c) 360
  27. 27.Best estimate of 131 + 340? (a) 200 (b) 600 (c) 400
  28. 28.Best estimate of 14 × 50? (a) 5000 (b) 50 (c) 500
  29. 29.Best estimate of 184 + 178? (a) 600 (b) 400 (c) 200
  30. 30.Best estimate of 29 × 67? (a) 21000 (b) 2100 (c) 210
  31. 31.Best estimate of 577 + 560? (a) 1000 (b) 1200 (c) 1400
  32. 32.Best estimate of 304 + 578? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 76 × 77? (a) 640 (b) 64000 (c) 6400
  34. 34.Best estimate of 558 + 212? (a) 1000 (b) 800 (c) 600
  35. 35.Best estimate of 566 + 421? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 56 × 46? (a) 30000 (b) 300 (c) 3000
  37. 37.Best estimate of 92 × 76? (a) 72000 (b) 7200 (c) 720
  38. 38.Best estimate of 49 × 62? (a) 30000 (b) 3000 (c) 300
  39. 39.Best estimate of 836 + 222? (a) 1200 (b) 800 (c) 1000
  40. 40.Best estimate of 22 × 76? (a) 1600 (b) 16000 (c) 160

Answer key

  1. 1300
  2. 500
  3. 800
  4. 1400
  5. 900
  6. 2400
  7. 1400
  8. 1400
  9. 900
  10. 1100
  11. 1300
  12. 600
  13. 4200
  14. 600
  15. 1400
  16. 1400
  17. 600
  18. 1400
  19. 800
  20. 1200
  21. 800
  22. 1200
  23. 1600
  24. 5400
  25. 4200
  26. 3600
  27. 400
  28. 500
  29. 400
  30. 2100
  31. 1200
  32. 900
  33. 6400
  34. 800
  35. 1000
  36. 3000
  37. 7200
  38. 3000
  39. 1000
  40. 1600

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