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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 98 · 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 154 + 139? (a) 300 (b) 100 (c) 500
  2. 2.Best estimate of 867 + 616? (a) 1700 (b) 1300 (c) 1500
  3. 3.Best estimate of 801 + 163? (a) 1200 (b) 800 (c) 1000
  4. 4.Best estimate of 46 × 82? (a) 40000 (b) 4000 (c) 400
  5. 5.Best estimate of 604 + 342? (a) 900 (b) 1100 (c) 700
  6. 6.Best estimate of 612 + 518? (a) 1300 (b) 1100 (c) 900
  7. 7.Best estimate of 270 + 631? (a) 700 (b) 900 (c) 1100
  8. 8.Best estimate of 46 × 12? (a) 5000 (b) 50 (c) 500
  9. 9.Best estimate of 59 × 76? (a) 4800 (b) 48000 (c) 480
  10. 10.Best estimate of 79 × 48? (a) 40000 (b) 4000 (c) 400
  11. 11.Best estimate of 26 × 38? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 789 + 466? (a) 1300 (b) 1500 (c) 1100
  13. 13.Best estimate of 783 + 376? (a) 1200 (b) 1000 (c) 1400
  14. 14.Best estimate of 56 × 26? (a) 1800 (b) 18000 (c) 180
  15. 15.Best estimate of 425 + 546? (a) 900 (b) 700 (c) 1100
  16. 16.Best estimate of 17 × 80? (a) 16000 (b) 1600 (c) 160
  17. 17.Best estimate of 93 × 26? (a) 2700 (b) 27000 (c) 270
  18. 18.Best estimate of 474 + 151? (a) 900 (b) 700 (c) 500
  19. 19.Best estimate of 41 × 28? (a) 1200 (b) 120 (c) 12000
  20. 20.Best estimate of 574 + 309? (a) 700 (b) 1100 (c) 900
  21. 21.Best estimate of 187 + 331? (a) 300 (b) 500 (c) 700
  22. 22.Best estimate of 83 × 26? (a) 240 (b) 24000 (c) 2400
  23. 23.Best estimate of 556 + 236? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 86 × 50? (a) 4500 (b) 450 (c) 45000
  25. 25.Best estimate of 22 × 42? (a) 8000 (b) 80 (c) 800
  26. 26.Best estimate of 324 + 516? (a) 600 (b) 1000 (c) 800
  27. 27.Best estimate of 535 + 272? (a) 1000 (b) 800 (c) 600
  28. 28.Best estimate of 50 × 43? (a) 200 (b) 2000 (c) 20000
  29. 29.Best estimate of 751 + 522? (a) 1100 (b) 1300 (c) 1500
  30. 30.Best estimate of 326 + 471? (a) 800 (b) 1000 (c) 600
  31. 31.Best estimate of 764 + 198? (a) 1200 (b) 800 (c) 1000
  32. 32.Best estimate of 300 + 266? (a) 800 (b) 600 (c) 400
  33. 33.Best estimate of 33 × 96? (a) 300 (b) 3000 (c) 30000
  34. 34.Best estimate of 569 + 778? (a) 1400 (b) 1600 (c) 1200
  35. 35.Best estimate of 678 + 366? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 59 × 66? (a) 42000 (b) 4200 (c) 420
  37. 37.Best estimate of 54 × 26? (a) 15000 (b) 1500 (c) 150
  38. 38.Best estimate of 46 × 59? (a) 300 (b) 3000 (c) 30000
  39. 39.Best estimate of 300 + 842? (a) 1100 (b) 900 (c) 1300
  40. 40.Best estimate of 20 × 66? (a) 1400 (b) 140 (c) 14000

Answer key

  1. 300
  2. 1500
  3. 1000
  4. 4000
  5. 900
  6. 1100
  7. 900
  8. 500
  9. 4800
  10. 4000
  11. 1200
  12. 1300
  13. 1200
  14. 1800
  15. 900
  16. 1600
  17. 2700
  18. 700
  19. 1200
  20. 900
  21. 500
  22. 2400
  23. 800
  24. 4500
  25. 800
  26. 800
  27. 800
  28. 2000
  29. 1300
  30. 800
  31. 1000
  32. 600
  33. 3000
  34. 1400
  35. 1100
  36. 4200
  37. 1500
  38. 3000
  39. 1100
  40. 1400

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