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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 209 · 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 86 × 61? (a) 5400 (b) 54000 (c) 540
  2. 2.Best estimate of 229 + 342? (a) 700 (b) 500 (c) 300
  3. 3.Best estimate of 462 + 157? (a) 900 (b) 500 (c) 700
  4. 4.Best estimate of 837 + 441? (a) 1000 (b) 1200 (c) 1400
  5. 5.Best estimate of 134 + 468? (a) 600 (b) 800 (c) 400
  6. 6.Best estimate of 14 × 31? (a) 3000 (b) 30 (c) 300
  7. 7.Best estimate of 625 + 836? (a) 1600 (b) 1400 (c) 1200
  8. 8.Best estimate of 805 + 843? (a) 1400 (b) 1600 (c) 1800
  9. 9.Best estimate of 41 × 52? (a) 20000 (b) 2000 (c) 200
  10. 10.Best estimate of 762 + 273? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 396 + 482? (a) 700 (b) 1100 (c) 900
  12. 12.Best estimate of 37 × 76? (a) 320 (b) 32000 (c) 3200
  13. 13.Best estimate of 21 × 18? (a) 4000 (b) 40 (c) 400
  14. 14.Best estimate of 30 × 63? (a) 18000 (b) 1800 (c) 180
  15. 15.Best estimate of 31 × 91? (a) 2700 (b) 27000 (c) 270
  16. 16.Best estimate of 518 + 495? (a) 800 (b) 1200 (c) 1000
  17. 17.Best estimate of 17 × 22? (a) 400 (b) 4000 (c) 40
  18. 18.Best estimate of 89 × 82? (a) 72000 (b) 720 (c) 7200
  19. 19.Best estimate of 801 + 434? (a) 1200 (b) 1000 (c) 1400
  20. 20.Best estimate of 679 + 571? (a) 1500 (b) 1300 (c) 1100
  21. 21.Best estimate of 729 + 567? (a) 1100 (b) 1300 (c) 1500
  22. 22.Best estimate of 566 + 205? (a) 1000 (b) 600 (c) 800
  23. 23.Best estimate of 66 × 64? (a) 420 (b) 42000 (c) 4200
  24. 24.Best estimate of 488 + 423? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 298 + 778? (a) 900 (b) 1300 (c) 1100
  26. 26.Best estimate of 86 × 28? (a) 270 (b) 2700 (c) 27000
  27. 27.Best estimate of 36 × 13? (a) 400 (b) 40 (c) 4000
  28. 28.Best estimate of 427 + 880? (a) 1300 (b) 1500 (c) 1100
  29. 29.Best estimate of 47 × 23? (a) 100 (b) 10000 (c) 1000
  30. 30.Best estimate of 144 + 296? (a) 600 (b) 400 (c) 200
  31. 31.Best estimate of 17 × 29? (a) 60 (b) 600 (c) 6000
  32. 32.Best estimate of 46 × 56? (a) 30000 (b) 300 (c) 3000
  33. 33.Best estimate of 17 × 26? (a) 600 (b) 6000 (c) 60
  34. 34.Best estimate of 423 + 258? (a) 500 (b) 700 (c) 900
  35. 35.Best estimate of 128 + 317? (a) 400 (b) 600 (c) 200
  36. 36.Best estimate of 839 + 700? (a) 1300 (b) 1700 (c) 1500
  37. 37.Best estimate of 159 + 257? (a) 500 (b) 700 (c) 300
  38. 38.Best estimate of 495 + 489? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 402 + 228? (a) 400 (b) 600 (c) 800
  40. 40.Best estimate of 385 + 626? (a) 800 (b) 1200 (c) 1000

Answer key

  1. 5400
  2. 500
  3. 700
  4. 1200
  5. 600
  6. 300
  7. 1400
  8. 1600
  9. 2000
  10. 1100
  11. 900
  12. 3200
  13. 400
  14. 1800
  15. 2700
  16. 1000
  17. 400
  18. 7200
  19. 1200
  20. 1300
  21. 1300
  22. 800
  23. 4200
  24. 900
  25. 1100
  26. 2700
  27. 400
  28. 1300
  29. 1000
  30. 400
  31. 600
  32. 3000
  33. 600
  34. 700
  35. 400
  36. 1500
  37. 500
  38. 1000
  39. 600
  40. 1000

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