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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 597 · 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 56 × 78? (a) 48000 (b) 480 (c) 4800
  2. 2.Best estimate of 661 + 152? (a) 900 (b) 700 (c) 1100
  3. 3.Best estimate of 690 + 756? (a) 1500 (b) 1700 (c) 1300
  4. 4.Best estimate of 226 + 294? (a) 700 (b) 300 (c) 500
  5. 5.Best estimate of 28 × 94? (a) 2700 (b) 270 (c) 27000
  6. 6.Best estimate of 558 + 448? (a) 1200 (b) 1000 (c) 800
  7. 7.Best estimate of 499 + 719? (a) 1400 (b) 1000 (c) 1200
  8. 8.Best estimate of 526 + 877? (a) 1400 (b) 1600 (c) 1200
  9. 9.Best estimate of 87 × 96? (a) 900 (b) 9000 (c) 90000
  10. 10.Best estimate of 515 + 803? (a) 1100 (b) 1500 (c) 1300
  11. 11.Best estimate of 166 + 704? (a) 700 (b) 900 (c) 1100
  12. 12.Best estimate of 241 + 455? (a) 700 (b) 900 (c) 500
  13. 13.Best estimate of 215 + 325? (a) 700 (b) 500 (c) 300
  14. 14.Best estimate of 76 × 58? (a) 480 (b) 48000 (c) 4800
  15. 15.Best estimate of 18 × 14? (a) 2000 (b) 200 (c) 20
  16. 16.Best estimate of 245 + 466? (a) 900 (b) 500 (c) 700
  17. 17.Best estimate of 661 + 770? (a) 1500 (b) 1300 (c) 1700
  18. 18.Best estimate of 90 × 78? (a) 7200 (b) 72000 (c) 720
  19. 19.Best estimate of 707 + 540? (a) 1000 (b) 1400 (c) 1200
  20. 20.Best estimate of 76 × 26? (a) 240 (b) 24000 (c) 2400
  21. 21.Best estimate of 41 × 28? (a) 12000 (b) 1200 (c) 120
  22. 22.Best estimate of 690 + 340? (a) 1200 (b) 800 (c) 1000
  23. 23.Best estimate of 527 + 425? (a) 1100 (b) 700 (c) 900
  24. 24.Best estimate of 72 × 17? (a) 14000 (b) 140 (c) 1400
  25. 25.Best estimate of 47 × 32? (a) 1500 (b) 15000 (c) 150
  26. 26.Best estimate of 82 × 74? (a) 5600 (b) 560 (c) 56000
  27. 27.Best estimate of 130 + 253? (a) 600 (b) 400 (c) 200
  28. 28.Best estimate of 730 + 368? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 138 + 879? (a) 1000 (b) 1200 (c) 800
  30. 30.Best estimate of 70 × 91? (a) 630 (b) 63000 (c) 6300
  31. 31.Best estimate of 76 × 19? (a) 16000 (b) 1600 (c) 160
  32. 32.Best estimate of 29 × 59? (a) 1800 (b) 180 (c) 18000
  33. 33.Best estimate of 64 × 50? (a) 300 (b) 3000 (c) 30000
  34. 34.Best estimate of 23 × 56? (a) 12000 (b) 1200 (c) 120
  35. 35.Best estimate of 345 + 389? (a) 500 (b) 700 (c) 900
  36. 36.Best estimate of 542 + 291? (a) 600 (b) 800 (c) 1000
  37. 37.Best estimate of 61 × 34? (a) 180 (b) 1800 (c) 18000
  38. 38.Best estimate of 33 × 56? (a) 180 (b) 18000 (c) 1800
  39. 39.Best estimate of 137 + 706? (a) 1000 (b) 800 (c) 600
  40. 40.Best estimate of 86 × 16? (a) 18000 (b) 1800 (c) 180

Answer key

  1. 4800
  2. 900
  3. 1500
  4. 500
  5. 2700
  6. 1000
  7. 1200
  8. 1400
  9. 9000
  10. 1300
  11. 900
  12. 700
  13. 500
  14. 4800
  15. 200
  16. 700
  17. 1500
  18. 7200
  19. 1200
  20. 2400
  21. 1200
  22. 1000
  23. 900
  24. 1400
  25. 1500
  26. 5600
  27. 400
  28. 1100
  29. 1000
  30. 6300
  31. 1600
  32. 1800
  33. 3000
  34. 1200
  35. 700
  36. 800
  37. 1800
  38. 1800
  39. 800
  40. 1800

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