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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 583 · 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 734 + 627? (a) 1300 (b) 1500 (c) 1100
  2. 2.Best estimate of 72 × 17? (a) 1400 (b) 140 (c) 14000
  3. 3.Best estimate of 66 × 36? (a) 280 (b) 28000 (c) 2800
  4. 4.Best estimate of 18 × 50? (a) 10000 (b) 1000 (c) 100
  5. 5.Best estimate of 78 × 26? (a) 240 (b) 2400 (c) 24000
  6. 6.Best estimate of 615 + 224? (a) 1000 (b) 800 (c) 600
  7. 7.Best estimate of 324 + 755? (a) 900 (b) 1100 (c) 1300
  8. 8.Best estimate of 161 + 337? (a) 300 (b) 700 (c) 500
  9. 9.Best estimate of 20 × 56? (a) 120 (b) 12000 (c) 1200
  10. 10.Best estimate of 448 + 401? (a) 1000 (b) 800 (c) 600
  11. 11.Best estimate of 30 × 78? (a) 240 (b) 24000 (c) 2400
  12. 12.Best estimate of 724 + 261? (a) 800 (b) 1200 (c) 1000
  13. 13.Best estimate of 46 × 46? (a) 25000 (b) 2500 (c) 250
  14. 14.Best estimate of 90 × 76? (a) 7200 (b) 72000 (c) 720
  15. 15.Best estimate of 398 + 203? (a) 400 (b) 800 (c) 600
  16. 16.Best estimate of 93 × 23? (a) 1800 (b) 18000 (c) 180
  17. 17.Best estimate of 472 + 302? (a) 600 (b) 800 (c) 1000
  18. 18.Best estimate of 32 × 31? (a) 900 (b) 9000 (c) 90
  19. 19.Best estimate of 80 × 16? (a) 16000 (b) 160 (c) 1600
  20. 20.Best estimate of 67 × 31? (a) 2100 (b) 210 (c) 21000
  21. 21.Best estimate of 435 + 859? (a) 1500 (b) 1100 (c) 1300
  22. 22.Best estimate of 88 × 36? (a) 3600 (b) 360 (c) 36000
  23. 23.Best estimate of 590 + 279? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 91 × 76? (a) 720 (b) 72000 (c) 7200
  25. 25.Best estimate of 96 × 49? (a) 500 (b) 5000 (c) 50000
  26. 26.Best estimate of 354 + 498? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 313 + 271? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 56 × 52? (a) 300 (b) 30000 (c) 3000
  29. 29.Best estimate of 227 + 376? (a) 400 (b) 600 (c) 800
  30. 30.Best estimate of 32 × 29? (a) 90 (b) 900 (c) 9000
  31. 31.Best estimate of 64 × 66? (a) 420 (b) 4200 (c) 42000
  32. 32.Best estimate of 80 × 90? (a) 7200 (b) 72000 (c) 720
  33. 33.Best estimate of 63 × 96? (a) 60000 (b) 600 (c) 6000
  34. 34.Best estimate of 297 + 502? (a) 600 (b) 1000 (c) 800
  35. 35.Best estimate of 566 + 259? (a) 700 (b) 1100 (c) 900
  36. 36.Best estimate of 79 × 66? (a) 56000 (b) 560 (c) 5600
  37. 37.Best estimate of 191 + 846? (a) 800 (b) 1000 (c) 1200
  38. 38.Best estimate of 89 × 26? (a) 270 (b) 2700 (c) 27000
  39. 39.Best estimate of 797 + 717? (a) 1500 (b) 1700 (c) 1300
  40. 40.Best estimate of 551 + 384? (a) 800 (b) 1200 (c) 1000

Answer key

  1. 1300
  2. 1400
  3. 2800
  4. 1000
  5. 2400
  6. 800
  7. 1100
  8. 500
  9. 1200
  10. 800
  11. 2400
  12. 1000
  13. 2500
  14. 7200
  15. 600
  16. 1800
  17. 800
  18. 900
  19. 1600
  20. 2100
  21. 1300
  22. 3600
  23. 900
  24. 7200
  25. 5000
  26. 900
  27. 600
  28. 3000
  29. 600
  30. 900
  31. 4200
  32. 7200
  33. 6000
  34. 800
  35. 900
  36. 5600
  37. 1000
  38. 2700
  39. 1500
  40. 1000

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