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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 136 · 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 56 × 66? (a) 4200 (b) 42000 (c) 420
  2. 2.Best estimate of 430 + 848? (a) 1200 (b) 1400 (c) 1000
  3. 3.Best estimate of 86 × 36? (a) 360 (b) 3600 (c) 36000
  4. 4.Best estimate of 79 × 18? (a) 16000 (b) 160 (c) 1600
  5. 5.Best estimate of 49 × 91? (a) 450 (b) 4500 (c) 45000
  6. 6.Best estimate of 657 + 538? (a) 1000 (b) 1200 (c) 1400
  7. 7.Best estimate of 244 + 577? (a) 1000 (b) 800 (c) 600
  8. 8.Best estimate of 18 × 76? (a) 1600 (b) 16000 (c) 160
  9. 9.Best estimate of 89 × 34? (a) 27000 (b) 2700 (c) 270
  10. 10.Best estimate of 686 + 314? (a) 1200 (b) 1000 (c) 800
  11. 11.Best estimate of 731 + 381? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 86 × 31? (a) 270 (b) 27000 (c) 2700
  13. 13.Best estimate of 24 × 97? (a) 20000 (b) 2000 (c) 200
  14. 14.Best estimate of 24 × 87? (a) 180 (b) 18000 (c) 1800
  15. 15.Best estimate of 503 + 226? (a) 700 (b) 500 (c) 900
  16. 16.Best estimate of 47 × 56? (a) 30000 (b) 3000 (c) 300
  17. 17.Best estimate of 651 + 497? (a) 1000 (b) 1200 (c) 1400
  18. 18.Best estimate of 198 + 340? (a) 700 (b) 300 (c) 500
  19. 19.Best estimate of 43 × 42? (a) 1600 (b) 160 (c) 16000
  20. 20.Best estimate of 22 × 93? (a) 1800 (b) 18000 (c) 180
  21. 21.Best estimate of 141 + 522? (a) 600 (b) 800 (c) 400
  22. 22.Best estimate of 525 + 456? (a) 800 (b) 1200 (c) 1000
  23. 23.Best estimate of 43 × 28? (a) 1200 (b) 120 (c) 12000
  24. 24.Best estimate of 16 × 12? (a) 20 (b) 200 (c) 2000
  25. 25.Best estimate of 696 + 129? (a) 800 (b) 1000 (c) 600
  26. 26.Best estimate of 53 × 56? (a) 30000 (b) 300 (c) 3000
  27. 27.Best estimate of 34 × 18? (a) 600 (b) 60 (c) 6000
  28. 28.Best estimate of 69 × 34? (a) 21000 (b) 210 (c) 2100
  29. 29.Best estimate of 207 + 832? (a) 800 (b) 1000 (c) 1200
  30. 30.Best estimate of 760 + 234? (a) 800 (b) 1200 (c) 1000
  31. 31.Best estimate of 60 × 17? (a) 120 (b) 12000 (c) 1200
  32. 32.Best estimate of 48 × 37? (a) 200 (b) 2000 (c) 20000
  33. 33.Best estimate of 801 + 459? (a) 1100 (b) 1500 (c) 1300
  34. 34.Best estimate of 122 + 426? (a) 500 (b) 300 (c) 700
  35. 35.Best estimate of 768 + 853? (a) 1500 (b) 1900 (c) 1700
  36. 36.Best estimate of 282 + 232? (a) 300 (b) 700 (c) 500
  37. 37.Best estimate of 32 × 58? (a) 18000 (b) 180 (c) 1800
  38. 38.Best estimate of 235 + 221? (a) 400 (b) 200 (c) 600
  39. 39.Best estimate of 194 + 220? (a) 400 (b) 200 (c) 600
  40. 40.Best estimate of 303 + 597? (a) 900 (b) 700 (c) 1100

Answer key

  1. 4200
  2. 1200
  3. 3600
  4. 1600
  5. 4500
  6. 1200
  7. 800
  8. 1600
  9. 2700
  10. 1000
  11. 1100
  12. 2700
  13. 2000
  14. 1800
  15. 700
  16. 3000
  17. 1200
  18. 500
  19. 1600
  20. 1800
  21. 600
  22. 1000
  23. 1200
  24. 200
  25. 800
  26. 3000
  27. 600
  28. 2100
  29. 1000
  30. 1000
  31. 1200
  32. 2000
  33. 1300
  34. 500
  35. 1700
  36. 500
  37. 1800
  38. 400
  39. 400
  40. 900

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