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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 588 · 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 90 × 96? (a) 900 (b) 9000 (c) 90000
  2. 2.Best estimate of 475 + 778? (a) 1500 (b) 1300 (c) 1100
  3. 3.Best estimate of 68 × 76? (a) 5600 (b) 56000 (c) 560
  4. 4.Best estimate of 28 × 92? (a) 27000 (b) 2700 (c) 270
  5. 5.Best estimate of 98 × 33? (a) 3000 (b) 300 (c) 30000
  6. 6.Best estimate of 52 × 46? (a) 2500 (b) 250 (c) 25000
  7. 7.Best estimate of 369 + 287? (a) 500 (b) 900 (c) 700
  8. 8.Best estimate of 332 + 290? (a) 600 (b) 800 (c) 400
  9. 9.Best estimate of 807 + 173? (a) 800 (b) 1000 (c) 1200
  10. 10.Best estimate of 27 × 92? (a) 270 (b) 2700 (c) 27000
  11. 11.Best estimate of 516 + 758? (a) 1300 (b) 1500 (c) 1100
  12. 12.Best estimate of 14 × 71? (a) 7000 (b) 70 (c) 700
  13. 13.Best estimate of 87 × 91? (a) 81000 (b) 810 (c) 8100
  14. 14.Best estimate of 39 × 61? (a) 240 (b) 2400 (c) 24000
  15. 15.Best estimate of 14 × 46? (a) 50 (b) 5000 (c) 500
  16. 16.Best estimate of 40 × 83? (a) 32000 (b) 320 (c) 3200
  17. 17.Best estimate of 787 + 651? (a) 1700 (b) 1300 (c) 1500
  18. 18.Best estimate of 48 × 93? (a) 45000 (b) 450 (c) 4500
  19. 19.Best estimate of 657 + 152? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 59 × 36? (a) 240 (b) 24000 (c) 2400
  21. 21.Best estimate of 26 × 29? (a) 9000 (b) 90 (c) 900
  22. 22.Best estimate of 90 × 93? (a) 8100 (b) 81000 (c) 810
  23. 23.Best estimate of 12 × 96? (a) 1000 (b) 100 (c) 10000
  24. 24.Best estimate of 49 × 66? (a) 350 (b) 3500 (c) 35000
  25. 25.Best estimate of 347 + 151? (a) 700 (b) 300 (c) 500
  26. 26.Best estimate of 71 × 62? (a) 4200 (b) 420 (c) 42000
  27. 27.Best estimate of 509 + 520? (a) 800 (b) 1000 (c) 1200
  28. 28.Best estimate of 643 + 354? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 82 × 94? (a) 72000 (b) 7200 (c) 720
  30. 30.Best estimate of 48 × 84? (a) 4000 (b) 40000 (c) 400
  31. 31.Best estimate of 618 + 121? (a) 700 (b) 900 (c) 500
  32. 32.Best estimate of 395 + 528? (a) 900 (b) 700 (c) 1100
  33. 33.Best estimate of 188 + 364? (a) 600 (b) 400 (c) 800
  34. 34.Best estimate of 546 + 405? (a) 900 (b) 700 (c) 1100
  35. 35.Best estimate of 684 + 415? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 414 + 303? (a) 500 (b) 700 (c) 900
  37. 37.Best estimate of 328 + 856? (a) 1400 (b) 1200 (c) 1000
  38. 38.Best estimate of 69 × 53? (a) 35000 (b) 3500 (c) 350
  39. 39.Best estimate of 261 + 651? (a) 1000 (b) 800 (c) 1200
  40. 40.Best estimate of 89 × 89? (a) 8100 (b) 81000 (c) 810

Answer key

  1. 9000
  2. 1300
  3. 5600
  4. 2700
  5. 3000
  6. 2500
  7. 700
  8. 600
  9. 1000
  10. 2700
  11. 1300
  12. 700
  13. 8100
  14. 2400
  15. 500
  16. 3200
  17. 1500
  18. 4500
  19. 900
  20. 2400
  21. 900
  22. 8100
  23. 1000
  24. 3500
  25. 500
  26. 4200
  27. 1000
  28. 1000
  29. 7200
  30. 4000
  31. 700
  32. 900
  33. 600
  34. 900
  35. 1100
  36. 700
  37. 1200
  38. 3500
  39. 1000
  40. 8100

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