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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 367 · 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 62 × 92? (a) 5400 (b) 540 (c) 54000
  2. 2.Best estimate of 614 + 560? (a) 1000 (b) 1200 (c) 1400
  3. 3.Best estimate of 38 × 59? (a) 24000 (b) 240 (c) 2400
  4. 4.Best estimate of 39 × 79? (a) 3200 (b) 320 (c) 32000
  5. 5.Best estimate of 60 × 69? (a) 42000 (b) 4200 (c) 420
  6. 6.Best estimate of 50 × 88? (a) 45000 (b) 450 (c) 4500
  7. 7.Best estimate of 62 × 86? (a) 540 (b) 5400 (c) 54000
  8. 8.Best estimate of 161 + 625? (a) 600 (b) 1000 (c) 800
  9. 9.Best estimate of 167 + 602? (a) 600 (b) 1000 (c) 800
  10. 10.Best estimate of 19 × 57? (a) 120 (b) 1200 (c) 12000
  11. 11.Best estimate of 44 × 78? (a) 32000 (b) 3200 (c) 320
  12. 12.Best estimate of 59 × 53? (a) 3000 (b) 300 (c) 30000
  13. 13.Best estimate of 306 + 872? (a) 1000 (b) 1400 (c) 1200
  14. 14.Best estimate of 72 × 44? (a) 28000 (b) 2800 (c) 280
  15. 15.Best estimate of 91 × 81? (a) 720 (b) 72000 (c) 7200
  16. 16.Best estimate of 795 + 704? (a) 1300 (b) 1500 (c) 1700
  17. 17.Best estimate of 48 × 20? (a) 10000 (b) 100 (c) 1000
  18. 18.Best estimate of 57 × 12? (a) 6000 (b) 60 (c) 600
  19. 19.Best estimate of 302 + 703? (a) 1000 (b) 800 (c) 1200
  20. 20.Best estimate of 91 × 32? (a) 27000 (b) 2700 (c) 270
  21. 21.Best estimate of 47 × 24? (a) 100 (b) 1000 (c) 10000
  22. 22.Best estimate of 127 + 840? (a) 700 (b) 900 (c) 1100
  23. 23.Best estimate of 24 × 48? (a) 100 (b) 1000 (c) 10000
  24. 24.Best estimate of 46 × 30? (a) 150 (b) 1500 (c) 15000
  25. 25.Best estimate of 51 × 24? (a) 1000 (b) 10000 (c) 100
  26. 26.Best estimate of 97 × 26? (a) 30000 (b) 300 (c) 3000
  27. 27.Best estimate of 872 + 679? (a) 1400 (b) 1600 (c) 1800
  28. 28.Best estimate of 87 × 32? (a) 27000 (b) 270 (c) 2700
  29. 29.Best estimate of 57 × 42? (a) 24000 (b) 240 (c) 2400
  30. 30.Best estimate of 349 + 646? (a) 900 (b) 1100 (c) 700
  31. 31.Best estimate of 22 × 62? (a) 120 (b) 1200 (c) 12000
  32. 32.Best estimate of 764 + 301? (a) 1300 (b) 900 (c) 1100
  33. 33.Best estimate of 16 × 14? (a) 200 (b) 20 (c) 2000
  34. 34.Best estimate of 502 + 806? (a) 1500 (b) 1300 (c) 1100
  35. 35.Best estimate of 31 × 22? (a) 6000 (b) 60 (c) 600
  36. 36.Best estimate of 46 × 12? (a) 500 (b) 5000 (c) 50
  37. 37.Best estimate of 732 + 688? (a) 1400 (b) 1600 (c) 1200
  38. 38.Best estimate of 479 + 743? (a) 1000 (b) 1200 (c) 1400
  39. 39.Best estimate of 56 × 58? (a) 3600 (b) 36000 (c) 360
  40. 40.Best estimate of 57 × 77? (a) 48000 (b) 4800 (c) 480

Answer key

  1. 5400
  2. 1200
  3. 2400
  4. 3200
  5. 4200
  6. 4500
  7. 5400
  8. 800
  9. 800
  10. 1200
  11. 3200
  12. 3000
  13. 1200
  14. 2800
  15. 7200
  16. 1500
  17. 1000
  18. 600
  19. 1000
  20. 2700
  21. 1000
  22. 900
  23. 1000
  24. 1500
  25. 1000
  26. 3000
  27. 1600
  28. 2700
  29. 2400
  30. 900
  31. 1200
  32. 1100
  33. 200
  34. 1300
  35. 600
  36. 500
  37. 1400
  38. 1200
  39. 3600
  40. 4800

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