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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 774 · 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 66 × 49? (a) 3500 (b) 350 (c) 35000
  2. 2.Best estimate of 534 + 182? (a) 900 (b) 700 (c) 500
  3. 3.Best estimate of 47 × 68? (a) 35000 (b) 3500 (c) 350
  4. 4.Best estimate of 206 + 141? (a) 500 (b) 300 (c) 100
  5. 5.Best estimate of 66 × 36? (a) 2800 (b) 28000 (c) 280
  6. 6.Best estimate of 61 × 60? (a) 3600 (b) 36000 (c) 360
  7. 7.Best estimate of 792 + 718? (a) 1500 (b) 1700 (c) 1300
  8. 8.Best estimate of 64 × 90? (a) 540 (b) 54000 (c) 5400
  9. 9.Best estimate of 205 + 383? (a) 400 (b) 600 (c) 800
  10. 10.Best estimate of 26 × 73? (a) 2100 (b) 21000 (c) 210
  11. 11.Best estimate of 78 × 58? (a) 480 (b) 48000 (c) 4800
  12. 12.Best estimate of 96 × 32? (a) 300 (b) 3000 (c) 30000
  13. 13.Best estimate of 26 × 29? (a) 90 (b) 9000 (c) 900
  14. 14.Best estimate of 254 + 798? (a) 900 (b) 1100 (c) 1300
  15. 15.Best estimate of 558 + 618? (a) 1200 (b) 1000 (c) 1400
  16. 16.Best estimate of 799 + 389? (a) 1200 (b) 1000 (c) 1400
  17. 17.Best estimate of 97 × 23? (a) 200 (b) 20000 (c) 2000
  18. 18.Best estimate of 34 × 64? (a) 18000 (b) 180 (c) 1800
  19. 19.Best estimate of 16 × 63? (a) 1200 (b) 120 (c) 12000
  20. 20.Best estimate of 599 + 621? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 666 + 831? (a) 1700 (b) 1500 (c) 1300
  22. 22.Best estimate of 88 × 12? (a) 90 (b) 9000 (c) 900
  23. 23.Best estimate of 386 + 136? (a) 300 (b) 500 (c) 700
  24. 24.Best estimate of 26 × 76? (a) 2400 (b) 24000 (c) 240
  25. 25.Best estimate of 735 + 219? (a) 700 (b) 900 (c) 1100
  26. 26.Best estimate of 84 × 54? (a) 400 (b) 40000 (c) 4000
  27. 27.Best estimate of 21 × 30? (a) 60 (b) 600 (c) 6000
  28. 28.Best estimate of 407 + 583? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 20 × 67? (a) 14000 (b) 1400 (c) 140
  30. 30.Best estimate of 214 + 509? (a) 700 (b) 900 (c) 500
  31. 31.Best estimate of 411 + 469? (a) 700 (b) 900 (c) 1100
  32. 32.Best estimate of 244 + 657? (a) 900 (b) 1100 (c) 700
  33. 33.Best estimate of 67 × 62? (a) 4200 (b) 420 (c) 42000
  34. 34.Best estimate of 74 × 78? (a) 56000 (b) 5600 (c) 560
  35. 35.Best estimate of 86 × 17? (a) 1800 (b) 180 (c) 18000
  36. 36.Best estimate of 841 + 796? (a) 1400 (b) 1600 (c) 1800
  37. 37.Best estimate of 204 + 300? (a) 500 (b) 700 (c) 300
  38. 38.Best estimate of 59 × 94? (a) 540 (b) 54000 (c) 5400
  39. 39.Best estimate of 86 × 81? (a) 720 (b) 72000 (c) 7200
  40. 40.Best estimate of 284 + 715? (a) 1200 (b) 800 (c) 1000

Answer key

  1. 3500
  2. 700
  3. 3500
  4. 300
  5. 2800
  6. 3600
  7. 1500
  8. 5400
  9. 600
  10. 2100
  11. 4800
  12. 3000
  13. 900
  14. 1100
  15. 1200
  16. 1200
  17. 2000
  18. 1800
  19. 1200
  20. 1200
  21. 1500
  22. 900
  23. 500
  24. 2400
  25. 900
  26. 4000
  27. 600
  28. 1000
  29. 1400
  30. 700
  31. 900
  32. 900
  33. 4200
  34. 5600
  35. 1800
  36. 1600
  37. 500
  38. 5400
  39. 7200
  40. 1000

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