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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 11 · 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 31 × 86? (a) 27000 (b) 270 (c) 2700
  2. 2.Best estimate of 147 + 316? (a) 600 (b) 200 (c) 400
  3. 3.Best estimate of 375 + 224? (a) 600 (b) 800 (c) 400
  4. 4.Best estimate of 94 × 98? (a) 90000 (b) 9000 (c) 900
  5. 5.Best estimate of 70 × 16? (a) 14000 (b) 1400 (c) 140
  6. 6.Best estimate of 21 × 79? (a) 1600 (b) 160 (c) 16000
  7. 7.Best estimate of 266 + 756? (a) 1300 (b) 900 (c) 1100
  8. 8.Best estimate of 842 + 391? (a) 1400 (b) 1000 (c) 1200
  9. 9.Best estimate of 193 + 729? (a) 1100 (b) 900 (c) 700
  10. 10.Best estimate of 46 × 16? (a) 10000 (b) 100 (c) 1000
  11. 11.Best estimate of 823 + 241? (a) 1200 (b) 800 (c) 1000
  12. 12.Best estimate of 386 + 507? (a) 1100 (b) 700 (c) 900
  13. 13.Best estimate of 517 + 229? (a) 900 (b) 500 (c) 700
  14. 14.Best estimate of 511 + 263? (a) 1000 (b) 800 (c) 600
  15. 15.Best estimate of 445 + 221? (a) 800 (b) 400 (c) 600
  16. 16.Best estimate of 860 + 802? (a) 1900 (b) 1700 (c) 1500
  17. 17.Best estimate of 328 + 234? (a) 500 (b) 300 (c) 700
  18. 18.Best estimate of 61 × 41? (a) 2400 (b) 24000 (c) 240
  19. 19.Best estimate of 226 + 205? (a) 400 (b) 600 (c) 200
  20. 20.Best estimate of 66 × 16? (a) 140 (b) 14000 (c) 1400
  21. 21.Best estimate of 215 + 857? (a) 1300 (b) 1100 (c) 900
  22. 22.Best estimate of 811 + 633? (a) 1400 (b) 1600 (c) 1200
  23. 23.Best estimate of 98 × 88? (a) 90000 (b) 900 (c) 9000
  24. 24.Best estimate of 44 × 68? (a) 2800 (b) 28000 (c) 280
  25. 25.Best estimate of 221 + 131? (a) 100 (b) 300 (c) 500
  26. 26.Best estimate of 84 × 12? (a) 80 (b) 8000 (c) 800
  27. 27.Best estimate of 480 + 821? (a) 1100 (b) 1500 (c) 1300
  28. 28.Best estimate of 66 × 41? (a) 2800 (b) 28000 (c) 280
  29. 29.Best estimate of 384 + 799? (a) 1200 (b) 1000 (c) 1400
  30. 30.Best estimate of 635 + 370? (a) 1000 (b) 800 (c) 1200
  31. 31.Best estimate of 16 × 72? (a) 14000 (b) 1400 (c) 140
  32. 32.Best estimate of 616 + 630? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 36 × 76? (a) 3200 (b) 320 (c) 32000
  34. 34.Best estimate of 91 × 16? (a) 1800 (b) 180 (c) 18000
  35. 35.Best estimate of 253 + 146? (a) 600 (b) 400 (c) 200
  36. 36.Best estimate of 67 × 50? (a) 350 (b) 35000 (c) 3500
  37. 37.Best estimate of 66 × 43? (a) 28000 (b) 280 (c) 2800
  38. 38.Best estimate of 720 + 160? (a) 1100 (b) 900 (c) 700
  39. 39.Best estimate of 831 + 148? (a) 900 (b) 1100 (c) 700
  40. 40.Best estimate of 70 × 59? (a) 420 (b) 42000 (c) 4200

Answer key

  1. 2700
  2. 400
  3. 600
  4. 9000
  5. 1400
  6. 1600
  7. 1100
  8. 1200
  9. 900
  10. 1000
  11. 1000
  12. 900
  13. 700
  14. 800
  15. 600
  16. 1700
  17. 500
  18. 2400
  19. 400
  20. 1400
  21. 1100
  22. 1400
  23. 9000
  24. 2800
  25. 300
  26. 800
  27. 1300
  28. 2800
  29. 1200
  30. 1000
  31. 1400
  32. 1200
  33. 3200
  34. 1800
  35. 400
  36. 3500
  37. 2800
  38. 900
  39. 900
  40. 4200

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