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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 738 · 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 488 + 646? (a) 1100 (b) 900 (c) 1300
  2. 2.Best estimate of 42 × 26? (a) 1200 (b) 12000 (c) 120
  3. 3.Best estimate of 20 × 56? (a) 120 (b) 1200 (c) 12000
  4. 4.Best estimate of 13 × 98? (a) 10000 (b) 1000 (c) 100
  5. 5.Best estimate of 26 × 72? (a) 2100 (b) 21000 (c) 210
  6. 6.Best estimate of 22 × 44? (a) 8000 (b) 80 (c) 800
  7. 7.Best estimate of 36 × 38? (a) 1600 (b) 16000 (c) 160
  8. 8.Best estimate of 48 × 36? (a) 20000 (b) 200 (c) 2000
  9. 9.Best estimate of 876 + 392? (a) 1300 (b) 1500 (c) 1100
  10. 10.Best estimate of 32 × 82? (a) 24000 (b) 2400 (c) 240
  11. 11.Best estimate of 671 + 189? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 761 + 474? (a) 1300 (b) 1100 (c) 1500
  13. 13.Best estimate of 558 + 570? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 81 × 46? (a) 4000 (b) 40000 (c) 400
  15. 15.Best estimate of 880 + 574? (a) 1500 (b) 1300 (c) 1700
  16. 16.Best estimate of 63 × 72? (a) 420 (b) 42000 (c) 4200
  17. 17.Best estimate of 802 + 743? (a) 1500 (b) 1300 (c) 1700
  18. 18.Best estimate of 24 × 89? (a) 180 (b) 1800 (c) 18000
  19. 19.Best estimate of 571 + 574? (a) 1200 (b) 1000 (c) 1400
  20. 20.Best estimate of 66 × 53? (a) 3500 (b) 35000 (c) 350
  21. 21.Best estimate of 790 + 302? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 151 + 258? (a) 300 (b) 700 (c) 500
  23. 23.Best estimate of 157 + 216? (a) 400 (b) 600 (c) 200
  24. 24.Best estimate of 91 × 17? (a) 18000 (b) 180 (c) 1800
  25. 25.Best estimate of 36 × 66? (a) 2800 (b) 28000 (c) 280
  26. 26.Best estimate of 829 + 263? (a) 1100 (b) 900 (c) 1300
  27. 27.Best estimate of 30 × 50? (a) 150 (b) 15000 (c) 1500
  28. 28.Best estimate of 36 × 81? (a) 32000 (b) 320 (c) 3200
  29. 29.Best estimate of 93 × 83? (a) 7200 (b) 72000 (c) 720
  30. 30.Best estimate of 198 + 320? (a) 500 (b) 300 (c) 700
  31. 31.Best estimate of 834 + 575? (a) 1600 (b) 1200 (c) 1400
  32. 32.Best estimate of 12 × 76? (a) 8000 (b) 80 (c) 800
  33. 33.Best estimate of 82 × 93? (a) 7200 (b) 72000 (c) 720
  34. 34.Best estimate of 669 + 440? (a) 1100 (b) 1300 (c) 900
  35. 35.Best estimate of 36 × 24? (a) 80 (b) 800 (c) 8000
  36. 36.Best estimate of 123 + 843? (a) 700 (b) 900 (c) 1100
  37. 37.Best estimate of 871 + 500? (a) 1400 (b) 1600 (c) 1200
  38. 38.Best estimate of 160 + 679? (a) 700 (b) 1100 (c) 900
  39. 39.Best estimate of 43 × 96? (a) 400 (b) 40000 (c) 4000
  40. 40.Best estimate of 484 + 437? (a) 900 (b) 700 (c) 1100

Answer key

  1. 1100
  2. 1200
  3. 1200
  4. 1000
  5. 2100
  6. 800
  7. 1600
  8. 2000
  9. 1300
  10. 2400
  11. 900
  12. 1300
  13. 1200
  14. 4000
  15. 1500
  16. 4200
  17. 1500
  18. 1800
  19. 1200
  20. 3500
  21. 1100
  22. 500
  23. 400
  24. 1800
  25. 2800
  26. 1100
  27. 1500
  28. 3200
  29. 7200
  30. 500
  31. 1400
  32. 800
  33. 7200
  34. 1100
  35. 800
  36. 900
  37. 1400
  38. 900
  39. 4000
  40. 900

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