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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 448 · 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 313 + 767? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 844 + 581? (a) 1600 (b) 1200 (c) 1400
  3. 3.Best estimate of 62 × 23? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 89 × 26? (a) 2700 (b) 270 (c) 27000
  5. 5.Best estimate of 71 × 90? (a) 6300 (b) 63000 (c) 630
  6. 6.Best estimate of 54 × 64? (a) 3000 (b) 300 (c) 30000
  7. 7.Best estimate of 46 × 70? (a) 3500 (b) 350 (c) 35000
  8. 8.Best estimate of 484 + 140? (a) 800 (b) 600 (c) 400
  9. 9.Best estimate of 64 × 98? (a) 600 (b) 60000 (c) 6000
  10. 10.Best estimate of 98 × 23? (a) 200 (b) 20000 (c) 2000
  11. 11.Best estimate of 438 + 478? (a) 1100 (b) 900 (c) 700
  12. 12.Best estimate of 14 × 77? (a) 800 (b) 8000 (c) 80
  13. 13.Best estimate of 59 × 34? (a) 18000 (b) 180 (c) 1800
  14. 14.Best estimate of 83 × 46? (a) 4000 (b) 40000 (c) 400
  15. 15.Best estimate of 41 × 26? (a) 1200 (b) 12000 (c) 120
  16. 16.Best estimate of 43 × 26? (a) 12000 (b) 1200 (c) 120
  17. 17.Best estimate of 77 × 18? (a) 16000 (b) 160 (c) 1600
  18. 18.Best estimate of 27 × 23? (a) 6000 (b) 60 (c) 600
  19. 19.Best estimate of 654 + 863? (a) 1800 (b) 1600 (c) 1400
  20. 20.Best estimate of 142 + 659? (a) 1000 (b) 800 (c) 600
  21. 21.Best estimate of 228 + 319? (a) 500 (b) 700 (c) 300
  22. 22.Best estimate of 16 × 86? (a) 18000 (b) 180 (c) 1800
  23. 23.Best estimate of 14 × 30? (a) 300 (b) 30 (c) 3000
  24. 24.Best estimate of 56 × 70? (a) 420 (b) 4200 (c) 42000
  25. 25.Best estimate of 135 + 619? (a) 700 (b) 900 (c) 500
  26. 26.Best estimate of 28 × 80? (a) 24000 (b) 240 (c) 2400
  27. 27.Best estimate of 43 × 77? (a) 3200 (b) 320 (c) 32000
  28. 28.Best estimate of 98 × 13? (a) 1000 (b) 100 (c) 10000
  29. 29.Best estimate of 562 + 219? (a) 800 (b) 1000 (c) 600
  30. 30.Best estimate of 22 × 93? (a) 180 (b) 18000 (c) 1800
  31. 31.Best estimate of 60 × 51? (a) 300 (b) 3000 (c) 30000
  32. 32.Best estimate of 743 + 787? (a) 1500 (b) 1700 (c) 1300
  33. 33.Best estimate of 363 + 298? (a) 900 (b) 700 (c) 500
  34. 34.Best estimate of 817 + 877? (a) 1700 (b) 1900 (c) 1500
  35. 35.Best estimate of 142 + 801? (a) 900 (b) 700 (c) 1100
  36. 36.Best estimate of 90 × 14? (a) 9000 (b) 900 (c) 90
  37. 37.Best estimate of 243 + 644? (a) 1000 (b) 600 (c) 800
  38. 38.Best estimate of 821 + 812? (a) 1400 (b) 1600 (c) 1800
  39. 39.Best estimate of 41 × 61? (a) 240 (b) 2400 (c) 24000
  40. 40.Best estimate of 66 × 14? (a) 7000 (b) 700 (c) 70

Answer key

  1. 1100
  2. 1400
  3. 1200
  4. 2700
  5. 6300
  6. 3000
  7. 3500
  8. 600
  9. 6000
  10. 2000
  11. 900
  12. 800
  13. 1800
  14. 4000
  15. 1200
  16. 1200
  17. 1600
  18. 600
  19. 1600
  20. 800
  21. 500
  22. 1800
  23. 300
  24. 4200
  25. 700
  26. 2400
  27. 3200
  28. 1000
  29. 800
  30. 1800
  31. 3000
  32. 1500
  33. 700
  34. 1700
  35. 900
  36. 900
  37. 800
  38. 1600
  39. 2400
  40. 700

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