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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 717 · 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 24 × 51? (a) 10000 (b) 100 (c) 1000
  2. 2.Best estimate of 128 + 848? (a) 900 (b) 700 (c) 1100
  3. 3.Best estimate of 156 + 217? (a) 400 (b) 600 (c) 200
  4. 4.Best estimate of 565 + 828? (a) 1600 (b) 1200 (c) 1400
  5. 5.Best estimate of 66 × 76? (a) 560 (b) 5600 (c) 56000
  6. 6.Best estimate of 571 + 345? (a) 700 (b) 1100 (c) 900
  7. 7.Best estimate of 20 × 60? (a) 1200 (b) 12000 (c) 120
  8. 8.Best estimate of 529 + 127? (a) 800 (b) 400 (c) 600
  9. 9.Best estimate of 46 × 33? (a) 150 (b) 15000 (c) 1500
  10. 10.Best estimate of 176 + 280? (a) 700 (b) 500 (c) 300
  11. 11.Best estimate of 732 + 665? (a) 1200 (b) 1400 (c) 1600
  12. 12.Best estimate of 30 × 87? (a) 2700 (b) 270 (c) 27000
  13. 13.Best estimate of 429 + 629? (a) 1200 (b) 1000 (c) 800
  14. 14.Best estimate of 41 × 70? (a) 2800 (b) 28000 (c) 280
  15. 15.Best estimate of 40 × 26? (a) 1200 (b) 12000 (c) 120
  16. 16.Best estimate of 28 × 57? (a) 18000 (b) 1800 (c) 180
  17. 17.Best estimate of 803 + 211? (a) 800 (b) 1000 (c) 1200
  18. 18.Best estimate of 63 × 32? (a) 1800 (b) 18000 (c) 180
  19. 19.Best estimate of 594 + 497? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 379 + 141? (a) 300 (b) 700 (c) 500
  21. 21.Best estimate of 43 × 66? (a) 28000 (b) 2800 (c) 280
  22. 22.Best estimate of 215 + 268? (a) 500 (b) 700 (c) 300
  23. 23.Best estimate of 26 × 41? (a) 1200 (b) 12000 (c) 120
  24. 24.Best estimate of 58 × 58? (a) 3600 (b) 36000 (c) 360
  25. 25.Best estimate of 91 × 60? (a) 54000 (b) 5400 (c) 540
  26. 26.Best estimate of 51 × 40? (a) 20000 (b) 200 (c) 2000
  27. 27.Best estimate of 578 + 255? (a) 900 (b) 700 (c) 1100
  28. 28.Best estimate of 90 × 36? (a) 3600 (b) 360 (c) 36000
  29. 29.Best estimate of 611 + 847? (a) 1200 (b) 1600 (c) 1400
  30. 30.Best estimate of 19 × 41? (a) 800 (b) 8000 (c) 80
  31. 31.Best estimate of 252 + 632? (a) 900 (b) 1100 (c) 700
  32. 32.Best estimate of 44 × 90? (a) 3600 (b) 360 (c) 36000
  33. 33.Best estimate of 16 × 63? (a) 12000 (b) 1200 (c) 120
  34. 34.Best estimate of 64 × 22? (a) 12000 (b) 120 (c) 1200
  35. 35.Best estimate of 87 × 94? (a) 81000 (b) 810 (c) 8100
  36. 36.Best estimate of 51 × 16? (a) 100 (b) 1000 (c) 10000
  37. 37.Best estimate of 27 × 79? (a) 24000 (b) 2400 (c) 240
  38. 38.Best estimate of 691 + 298? (a) 800 (b) 1200 (c) 1000
  39. 39.Best estimate of 444 + 377? (a) 1000 (b) 800 (c) 600
  40. 40.Best estimate of 730 + 547? (a) 1400 (b) 1000 (c) 1200

Answer key

  1. 1000
  2. 900
  3. 400
  4. 1400
  5. 5600
  6. 900
  7. 1200
  8. 600
  9. 1500
  10. 500
  11. 1400
  12. 2700
  13. 1000
  14. 2800
  15. 1200
  16. 1800
  17. 1000
  18. 1800
  19. 1100
  20. 500
  21. 2800
  22. 500
  23. 1200
  24. 3600
  25. 5400
  26. 2000
  27. 900
  28. 3600
  29. 1400
  30. 800
  31. 900
  32. 3600
  33. 1200
  34. 1200
  35. 8100
  36. 1000
  37. 2400
  38. 1000
  39. 800
  40. 1200

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