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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 842 · 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 491 + 617? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 16 × 46? (a) 10000 (b) 1000 (c) 100
  3. 3.Best estimate of 76 × 51? (a) 4000 (b) 400 (c) 40000
  4. 4.Best estimate of 709 + 293? (a) 1000 (b) 1200 (c) 800
  5. 5.Best estimate of 666 + 395? (a) 1300 (b) 1100 (c) 900
  6. 6.Best estimate of 503 + 193? (a) 700 (b) 500 (c) 900
  7. 7.Best estimate of 216 + 383? (a) 400 (b) 600 (c) 800
  8. 8.Best estimate of 83 × 73? (a) 56000 (b) 560 (c) 5600
  9. 9.Best estimate of 514 + 443? (a) 900 (b) 700 (c) 1100
  10. 10.Best estimate of 76 × 77? (a) 64000 (b) 6400 (c) 640
  11. 11.Best estimate of 120 + 420? (a) 300 (b) 700 (c) 500
  12. 12.Best estimate of 80 × 22? (a) 160 (b) 16000 (c) 1600
  13. 13.Best estimate of 271 + 479? (a) 800 (b) 600 (c) 1000
  14. 14.Best estimate of 56 × 40? (a) 240 (b) 24000 (c) 2400
  15. 15.Best estimate of 33 × 94? (a) 2700 (b) 270 (c) 27000
  16. 16.Best estimate of 36 × 49? (a) 2000 (b) 20000 (c) 200
  17. 17.Best estimate of 29 × 77? (a) 24000 (b) 2400 (c) 240
  18. 18.Best estimate of 13 × 52? (a) 50 (b) 5000 (c) 500
  19. 19.Best estimate of 527 + 436? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 71 × 17? (a) 1400 (b) 14000 (c) 140
  21. 21.Best estimate of 76 × 72? (a) 560 (b) 56000 (c) 5600
  22. 22.Best estimate of 31 × 96? (a) 3000 (b) 30000 (c) 300
  23. 23.Best estimate of 868 + 678? (a) 1400 (b) 1600 (c) 1800
  24. 24.Best estimate of 636 + 366? (a) 800 (b) 1000 (c) 1200
  25. 25.Best estimate of 270 + 387? (a) 900 (b) 700 (c) 500
  26. 26.Best estimate of 200 + 286? (a) 700 (b) 300 (c) 500
  27. 27.Best estimate of 357 + 693? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 90 × 17? (a) 1800 (b) 180 (c) 18000
  29. 29.Best estimate of 30 × 78? (a) 240 (b) 24000 (c) 2400
  30. 30.Best estimate of 558 + 702? (a) 1500 (b) 1100 (c) 1300
  31. 31.Best estimate of 96 × 26? (a) 30000 (b) 300 (c) 3000
  32. 32.Best estimate of 64 × 71? (a) 420 (b) 42000 (c) 4200
  33. 33.Best estimate of 621 + 839? (a) 1600 (b) 1200 (c) 1400
  34. 34.Best estimate of 76 × 40? (a) 32000 (b) 320 (c) 3200
  35. 35.Best estimate of 210 + 451? (a) 700 (b) 900 (c) 500
  36. 36.Best estimate of 24 × 12? (a) 20 (b) 200 (c) 2000
  37. 37.Best estimate of 327 + 335? (a) 800 (b) 400 (c) 600
  38. 38.Best estimate of 560 + 815? (a) 1600 (b) 1200 (c) 1400
  39. 39.Best estimate of 449 + 323? (a) 900 (b) 500 (c) 700
  40. 40.Best estimate of 856 + 751? (a) 1900 (b) 1500 (c) 1700

Answer key

  1. 1100
  2. 1000
  3. 4000
  4. 1000
  5. 1100
  6. 700
  7. 600
  8. 5600
  9. 900
  10. 6400
  11. 500
  12. 1600
  13. 800
  14. 2400
  15. 2700
  16. 2000
  17. 2400
  18. 500
  19. 900
  20. 1400
  21. 5600
  22. 3000
  23. 1600
  24. 1000
  25. 700
  26. 500
  27. 1100
  28. 1800
  29. 2400
  30. 1300
  31. 3000
  32. 4200
  33. 1400
  34. 3200
  35. 700
  36. 200
  37. 600
  38. 1400
  39. 700
  40. 1700

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