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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 851 · 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 92 × 27? (a) 27000 (b) 2700 (c) 270
  2. 2.Best estimate of 21 × 62? (a) 1200 (b) 12000 (c) 120
  3. 3.Best estimate of 391 + 493? (a) 1100 (b) 700 (c) 900
  4. 4.Best estimate of 223 + 635? (a) 600 (b) 800 (c) 1000
  5. 5.Best estimate of 371 + 805? (a) 1400 (b) 1200 (c) 1000
  6. 6.Best estimate of 49 × 18? (a) 10000 (b) 1000 (c) 100
  7. 7.Best estimate of 341 + 567? (a) 700 (b) 1100 (c) 900
  8. 8.Best estimate of 377 + 852? (a) 1300 (b) 1500 (c) 1100
  9. 9.Best estimate of 26 × 13? (a) 3000 (b) 30 (c) 300
  10. 10.Best estimate of 31 × 76? (a) 240 (b) 24000 (c) 2400
  11. 11.Best estimate of 96 × 28? (a) 300 (b) 30000 (c) 3000
  12. 12.Best estimate of 32 × 48? (a) 150 (b) 15000 (c) 1500
  13. 13.Best estimate of 371 + 678? (a) 1100 (b) 1300 (c) 900
  14. 14.Best estimate of 559 + 616? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 44 × 39? (a) 1600 (b) 16000 (c) 160
  16. 16.Best estimate of 98 × 64? (a) 600 (b) 6000 (c) 60000
  17. 17.Best estimate of 26 × 12? (a) 30 (b) 3000 (c) 300
  18. 18.Best estimate of 709 + 854? (a) 1800 (b) 1600 (c) 1400
  19. 19.Best estimate of 70 × 77? (a) 560 (b) 5600 (c) 56000
  20. 20.Best estimate of 37 × 87? (a) 3600 (b) 36000 (c) 360
  21. 21.Best estimate of 52 × 91? (a) 450 (b) 45000 (c) 4500
  22. 22.Best estimate of 357 + 677? (a) 1300 (b) 900 (c) 1100
  23. 23.Best estimate of 96 × 52? (a) 5000 (b) 500 (c) 50000
  24. 24.Best estimate of 16 × 72? (a) 1400 (b) 14000 (c) 140
  25. 25.Best estimate of 554 + 725? (a) 1500 (b) 1300 (c) 1100
  26. 26.Best estimate of 628 + 565? (a) 1400 (b) 1200 (c) 1000
  27. 27.Best estimate of 660 + 707? (a) 1200 (b) 1400 (c) 1600
  28. 28.Best estimate of 544 + 277? (a) 800 (b) 1000 (c) 600
  29. 29.Best estimate of 46 × 53? (a) 25000 (b) 250 (c) 2500
  30. 30.Best estimate of 30 × 88? (a) 27000 (b) 2700 (c) 270
  31. 31.Best estimate of 16 × 36? (a) 80 (b) 8000 (c) 800
  32. 32.Best estimate of 12 × 86? (a) 90 (b) 900 (c) 9000
  33. 33.Best estimate of 20 × 88? (a) 18000 (b) 180 (c) 1800
  34. 34.Best estimate of 30 × 44? (a) 1200 (b) 120 (c) 12000
  35. 35.Best estimate of 839 + 735? (a) 1300 (b) 1500 (c) 1700
  36. 36.Best estimate of 82 × 12? (a) 80 (b) 8000 (c) 800
  37. 37.Best estimate of 767 + 184? (a) 1200 (b) 1000 (c) 800
  38. 38.Best estimate of 19 × 46? (a) 100 (b) 10000 (c) 1000
  39. 39.Best estimate of 714 + 237? (a) 900 (b) 700 (c) 1100
  40. 40.Best estimate of 184 + 349? (a) 300 (b) 500 (c) 700

Answer key

  1. 2700
  2. 1200
  3. 900
  4. 800
  5. 1200
  6. 1000
  7. 900
  8. 1300
  9. 300
  10. 2400
  11. 3000
  12. 1500
  13. 1100
  14. 1200
  15. 1600
  16. 6000
  17. 300
  18. 1600
  19. 5600
  20. 3600
  21. 4500
  22. 1100
  23. 5000
  24. 1400
  25. 1300
  26. 1200
  27. 1400
  28. 800
  29. 2500
  30. 2700
  31. 800
  32. 900
  33. 1800
  34. 1200
  35. 1500
  36. 800
  37. 1000
  38. 1000
  39. 900
  40. 500

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