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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 802 · 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 335 + 641? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 708 + 403? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 78 × 91? (a) 72000 (b) 7200 (c) 720
  4. 4.Best estimate of 87 × 12? (a) 90 (b) 9000 (c) 900
  5. 5.Best estimate of 843 + 375? (a) 1400 (b) 1200 (c) 1000
  6. 6.Best estimate of 21 × 47? (a) 1000 (b) 10000 (c) 100
  7. 7.Best estimate of 471 + 851? (a) 1600 (b) 1200 (c) 1400
  8. 8.Best estimate of 74 × 53? (a) 3500 (b) 350 (c) 35000
  9. 9.Best estimate of 418 + 209? (a) 800 (b) 400 (c) 600
  10. 10.Best estimate of 786 + 729? (a) 1700 (b) 1300 (c) 1500
  11. 11.Best estimate of 777 + 797? (a) 1400 (b) 1800 (c) 1600
  12. 12.Best estimate of 353 + 744? (a) 1300 (b) 1100 (c) 900
  13. 13.Best estimate of 18 × 26? (a) 600 (b) 6000 (c) 60
  14. 14.Best estimate of 505 + 155? (a) 900 (b) 500 (c) 700
  15. 15.Best estimate of 84 × 33? (a) 240 (b) 24000 (c) 2400
  16. 16.Best estimate of 24 × 97? (a) 2000 (b) 200 (c) 20000
  17. 17.Best estimate of 252 + 746? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 736 + 260? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 218 + 212? (a) 200 (b) 400 (c) 600
  20. 20.Best estimate of 18 × 91? (a) 18000 (b) 180 (c) 1800
  21. 21.Best estimate of 82 × 89? (a) 72000 (b) 720 (c) 7200
  22. 22.Best estimate of 67 × 98? (a) 700 (b) 70000 (c) 7000
  23. 23.Best estimate of 71 × 49? (a) 3500 (b) 350 (c) 35000
  24. 24.Best estimate of 430 + 135? (a) 300 (b) 700 (c) 500
  25. 25.Best estimate of 208 + 395? (a) 600 (b) 800 (c) 400
  26. 26.Best estimate of 651 + 181? (a) 700 (b) 1100 (c) 900
  27. 27.Best estimate of 428 + 201? (a) 800 (b) 400 (c) 600
  28. 28.Best estimate of 321 + 781? (a) 1100 (b) 1300 (c) 900
  29. 29.Best estimate of 234 + 166? (a) 600 (b) 200 (c) 400
  30. 30.Best estimate of 161 + 127? (a) 300 (b) 500 (c) 100
  31. 31.Best estimate of 864 + 405? (a) 1300 (b) 1500 (c) 1100
  32. 32.Best estimate of 83 × 19? (a) 16000 (b) 160 (c) 1600
  33. 33.Best estimate of 72 × 94? (a) 63000 (b) 630 (c) 6300
  34. 34.Best estimate of 637 + 205? (a) 1000 (b) 800 (c) 600
  35. 35.Best estimate of 262 + 329? (a) 400 (b) 600 (c) 800
  36. 36.Best estimate of 175 + 679? (a) 900 (b) 1100 (c) 700
  37. 37.Best estimate of 79 × 17? (a) 1600 (b) 16000 (c) 160
  38. 38.Best estimate of 76 × 13? (a) 80 (b) 8000 (c) 800
  39. 39.Best estimate of 66 × 76? (a) 560 (b) 56000 (c) 5600
  40. 40.Best estimate of 329 + 643? (a) 700 (b) 1100 (c) 900

Answer key

  1. 900
  2. 1100
  3. 7200
  4. 900
  5. 1200
  6. 1000
  7. 1400
  8. 3500
  9. 600
  10. 1500
  11. 1600
  12. 1100
  13. 600
  14. 700
  15. 2400
  16. 2000
  17. 1000
  18. 1000
  19. 400
  20. 1800
  21. 7200
  22. 7000
  23. 3500
  24. 500
  25. 600
  26. 900
  27. 600
  28. 1100
  29. 400
  30. 300
  31. 1300
  32. 1600
  33. 6300
  34. 800
  35. 600
  36. 900
  37. 1600
  38. 800
  39. 5600
  40. 900

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