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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 715 · 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 352 + 554? (a) 1000 (b) 800 (c) 1200
  2. 2.Best estimate of 70 × 29? (a) 21000 (b) 210 (c) 2100
  3. 3.Best estimate of 87 × 63? (a) 54000 (b) 540 (c) 5400
  4. 4.Best estimate of 26 × 74? (a) 210 (b) 2100 (c) 21000
  5. 5.Best estimate of 97 × 48? (a) 5000 (b) 500 (c) 50000
  6. 6.Best estimate of 732 + 758? (a) 1300 (b) 1500 (c) 1700
  7. 7.Best estimate of 63 × 73? (a) 420 (b) 42000 (c) 4200
  8. 8.Best estimate of 348 + 691? (a) 800 (b) 1000 (c) 1200
  9. 9.Best estimate of 59 × 19? (a) 12000 (b) 120 (c) 1200
  10. 10.Best estimate of 263 + 458? (a) 600 (b) 1000 (c) 800
  11. 11.Best estimate of 389 + 358? (a) 600 (b) 800 (c) 1000
  12. 12.Best estimate of 52 × 36? (a) 200 (b) 2000 (c) 20000
  13. 13.Best estimate of 16 × 37? (a) 800 (b) 80 (c) 8000
  14. 14.Best estimate of 80 × 79? (a) 6400 (b) 640 (c) 64000
  15. 15.Best estimate of 480 + 193? (a) 500 (b) 900 (c) 700
  16. 16.Best estimate of 18 × 33? (a) 6000 (b) 600 (c) 60
  17. 17.Best estimate of 651 + 616? (a) 1300 (b) 1100 (c) 1500
  18. 18.Best estimate of 418 + 492? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 449 + 672? (a) 900 (b) 1100 (c) 1300
  20. 20.Best estimate of 32 × 36? (a) 12000 (b) 1200 (c) 120
  21. 21.Best estimate of 606 + 331? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 24 × 80? (a) 160 (b) 16000 (c) 1600
  23. 23.Best estimate of 513 + 747? (a) 1000 (b) 1400 (c) 1200
  24. 24.Best estimate of 52 × 86? (a) 450 (b) 4500 (c) 45000
  25. 25.Best estimate of 90 × 57? (a) 540 (b) 5400 (c) 54000
  26. 26.Best estimate of 92 × 96? (a) 900 (b) 9000 (c) 90000
  27. 27.Best estimate of 86 × 14? (a) 900 (b) 90 (c) 9000
  28. 28.Best estimate of 24 × 48? (a) 100 (b) 10000 (c) 1000
  29. 29.Best estimate of 556 + 321? (a) 1100 (b) 900 (c) 700
  30. 30.Best estimate of 621 + 668? (a) 1300 (b) 1100 (c) 1500
  31. 31.Best estimate of 47 × 13? (a) 5000 (b) 500 (c) 50
  32. 32.Best estimate of 13 × 46? (a) 50 (b) 5000 (c) 500
  33. 33.Best estimate of 90 × 73? (a) 63000 (b) 630 (c) 6300
  34. 34.Best estimate of 28 × 17? (a) 600 (b) 60 (c) 6000
  35. 35.Best estimate of 617 + 685? (a) 1500 (b) 1300 (c) 1100
  36. 36.Best estimate of 76 × 96? (a) 800 (b) 8000 (c) 80000
  37. 37.Best estimate of 96 × 24? (a) 200 (b) 20000 (c) 2000
  38. 38.Best estimate of 135 + 218? (a) 300 (b) 500 (c) 100
  39. 39.Best estimate of 31 × 67? (a) 210 (b) 21000 (c) 2100
  40. 40.Best estimate of 70 × 71? (a) 49000 (b) 490 (c) 4900

Answer key

  1. 1000
  2. 2100
  3. 5400
  4. 2100
  5. 5000
  6. 1500
  7. 4200
  8. 1000
  9. 1200
  10. 800
  11. 800
  12. 2000
  13. 800
  14. 6400
  15. 700
  16. 600
  17. 1300
  18. 900
  19. 1100
  20. 1200
  21. 900
  22. 1600
  23. 1200
  24. 4500
  25. 5400
  26. 9000
  27. 900
  28. 1000
  29. 900
  30. 1300
  31. 500
  32. 500
  33. 6300
  34. 600
  35. 1300
  36. 8000
  37. 2000
  38. 300
  39. 2100
  40. 4900

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