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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 777 · 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 560 + 161? (a) 800 (b) 600 (c) 1000
  2. 2.Best estimate of 212 + 451? (a) 900 (b) 500 (c) 700
  3. 3.Best estimate of 23 × 44? (a) 80 (b) 8000 (c) 800
  4. 4.Best estimate of 471 + 559? (a) 1100 (b) 1300 (c) 900
  5. 5.Best estimate of 83 × 19? (a) 160 (b) 1600 (c) 16000
  6. 6.Best estimate of 40 × 96? (a) 4000 (b) 400 (c) 40000
  7. 7.Best estimate of 534 + 551? (a) 1100 (b) 900 (c) 1300
  8. 8.Best estimate of 654 + 785? (a) 1700 (b) 1500 (c) 1300
  9. 9.Best estimate of 840 + 595? (a) 1400 (b) 1600 (c) 1200
  10. 10.Best estimate of 685 + 873? (a) 1800 (b) 1400 (c) 1600
  11. 11.Best estimate of 32 × 97? (a) 3000 (b) 30000 (c) 300
  12. 12.Best estimate of 836 + 165? (a) 800 (b) 1000 (c) 1200
  13. 13.Best estimate of 391 + 593? (a) 1200 (b) 800 (c) 1000
  14. 14.Best estimate of 16 × 56? (a) 1200 (b) 12000 (c) 120
  15. 15.Best estimate of 69 × 74? (a) 49000 (b) 4900 (c) 490
  16. 16.Best estimate of 16 × 18? (a) 4000 (b) 400 (c) 40
  17. 17.Best estimate of 406 + 196? (a) 800 (b) 600 (c) 400
  18. 18.Best estimate of 713 + 729? (a) 1600 (b) 1400 (c) 1200
  19. 19.Best estimate of 36 × 46? (a) 200 (b) 2000 (c) 20000
  20. 20.Best estimate of 569 + 124? (a) 700 (b) 900 (c) 500
  21. 21.Best estimate of 589 + 154? (a) 1000 (b) 800 (c) 600
  22. 22.Best estimate of 83 × 60? (a) 480 (b) 4800 (c) 48000
  23. 23.Best estimate of 23 × 12? (a) 20 (b) 200 (c) 2000
  24. 24.Best estimate of 91 × 16? (a) 1800 (b) 180 (c) 18000
  25. 25.Best estimate of 76 × 67? (a) 5600 (b) 560 (c) 56000
  26. 26.Best estimate of 196 + 651? (a) 900 (b) 1100 (c) 700
  27. 27.Best estimate of 88 × 66? (a) 630 (b) 6300 (c) 63000
  28. 28.Best estimate of 92 × 66? (a) 630 (b) 6300 (c) 63000
  29. 29.Best estimate of 26 × 59? (a) 1800 (b) 180 (c) 18000
  30. 30.Best estimate of 186 + 820? (a) 800 (b) 1200 (c) 1000
  31. 31.Best estimate of 97 × 91? (a) 900 (b) 90000 (c) 9000
  32. 32.Best estimate of 217 + 356? (a) 400 (b) 600 (c) 800
  33. 33.Best estimate of 329 + 758? (a) 1300 (b) 900 (c) 1100
  34. 34.Best estimate of 21 × 12? (a) 200 (b) 20 (c) 2000
  35. 35.Best estimate of 77 × 94? (a) 7200 (b) 72000 (c) 720
  36. 36.Best estimate of 93 × 59? (a) 54000 (b) 5400 (c) 540
  37. 37.Best estimate of 125 + 527? (a) 600 (b) 800 (c) 400
  38. 38.Best estimate of 31 × 33? (a) 90 (b) 900 (c) 9000
  39. 39.Best estimate of 424 + 717? (a) 1100 (b) 1300 (c) 900
  40. 40.Best estimate of 53 × 62? (a) 30000 (b) 3000 (c) 300

Answer key

  1. 800
  2. 700
  3. 800
  4. 1100
  5. 1600
  6. 4000
  7. 1100
  8. 1500
  9. 1400
  10. 1600
  11. 3000
  12. 1000
  13. 1000
  14. 1200
  15. 4900
  16. 400
  17. 600
  18. 1400
  19. 2000
  20. 700
  21. 800
  22. 4800
  23. 200
  24. 1800
  25. 5600
  26. 900
  27. 6300
  28. 6300
  29. 1800
  30. 1000
  31. 9000
  32. 600
  33. 1100
  34. 200
  35. 7200
  36. 5400
  37. 600
  38. 900
  39. 1100
  40. 3000

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