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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 51 · 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 54 × 56? (a) 30000 (b) 3000 (c) 300
  2. 2.Best estimate of 47 × 41? (a) 20000 (b) 200 (c) 2000
  3. 3.Best estimate of 78 × 40? (a) 320 (b) 3200 (c) 32000
  4. 4.Best estimate of 247 + 200? (a) 400 (b) 600 (c) 200
  5. 5.Best estimate of 19 × 91? (a) 180 (b) 1800 (c) 18000
  6. 6.Best estimate of 509 + 219? (a) 500 (b) 900 (c) 700
  7. 7.Best estimate of 22 × 31? (a) 60 (b) 6000 (c) 600
  8. 8.Best estimate of 84 × 16? (a) 160 (b) 1600 (c) 16000
  9. 9.Best estimate of 595 + 728? (a) 1500 (b) 1300 (c) 1100
  10. 10.Best estimate of 16 × 63? (a) 1200 (b) 120 (c) 12000
  11. 11.Best estimate of 24 × 96? (a) 20000 (b) 2000 (c) 200
  12. 12.Best estimate of 447 + 807? (a) 1400 (b) 1200 (c) 1000
  13. 13.Best estimate of 479 + 226? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 71 × 20? (a) 1400 (b) 14000 (c) 140
  15. 15.Best estimate of 43 × 33? (a) 1200 (b) 120 (c) 12000
  16. 16.Best estimate of 336 + 630? (a) 700 (b) 900 (c) 1100
  17. 17.Best estimate of 12 × 77? (a) 8000 (b) 80 (c) 800
  18. 18.Best estimate of 265 + 336? (a) 800 (b) 600 (c) 400
  19. 19.Best estimate of 813 + 849? (a) 1800 (b) 1400 (c) 1600
  20. 20.Best estimate of 582 + 522? (a) 900 (b) 1100 (c) 1300
  21. 21.Best estimate of 239 + 862? (a) 1300 (b) 1100 (c) 900
  22. 22.Best estimate of 735 + 296? (a) 1000 (b) 1200 (c) 800
  23. 23.Best estimate of 345 + 467? (a) 1000 (b) 600 (c) 800
  24. 24.Best estimate of 400 + 552? (a) 1200 (b) 1000 (c) 800
  25. 25.Best estimate of 18 × 56? (a) 12000 (b) 1200 (c) 120
  26. 26.Best estimate of 43 × 41? (a) 16000 (b) 1600 (c) 160
  27. 27.Best estimate of 13 × 66? (a) 70 (b) 7000 (c) 700
  28. 28.Best estimate of 137 + 534? (a) 400 (b) 600 (c) 800
  29. 29.Best estimate of 26 × 14? (a) 300 (b) 3000 (c) 30
  30. 30.Best estimate of 297 + 713? (a) 1200 (b) 1000 (c) 800
  31. 31.Best estimate of 94 × 24? (a) 180 (b) 18000 (c) 1800
  32. 32.Best estimate of 70 × 94? (a) 63000 (b) 630 (c) 6300
  33. 33.Best estimate of 13 × 51? (a) 5000 (b) 500 (c) 50
  34. 34.Best estimate of 92 × 49? (a) 45000 (b) 450 (c) 4500
  35. 35.Best estimate of 435 + 611? (a) 1000 (b) 800 (c) 1200
  36. 36.Best estimate of 415 + 426? (a) 800 (b) 1000 (c) 600
  37. 37.Best estimate of 67 × 40? (a) 2800 (b) 280 (c) 28000
  38. 38.Best estimate of 474 + 384? (a) 900 (b) 700 (c) 1100
  39. 39.Best estimate of 42 × 91? (a) 36000 (b) 360 (c) 3600
  40. 40.Best estimate of 837 + 393? (a) 1200 (b) 1000 (c) 1400

Answer key

  1. 3000
  2. 2000
  3. 3200
  4. 400
  5. 1800
  6. 700
  7. 600
  8. 1600
  9. 1300
  10. 1200
  11. 2000
  12. 1200
  13. 700
  14. 1400
  15. 1200
  16. 900
  17. 800
  18. 600
  19. 1600
  20. 1100
  21. 1100
  22. 1000
  23. 800
  24. 1000
  25. 1200
  26. 1600
  27. 700
  28. 600
  29. 300
  30. 1000
  31. 1800
  32. 6300
  33. 500
  34. 4500
  35. 1000
  36. 800
  37. 2800
  38. 900
  39. 3600
  40. 1200

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