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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 366 · 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 779 + 213? (a) 1200 (b) 800 (c) 1000
  2. 2.Best estimate of 136 + 144? (a) 400 (b) 200 (c) 0
  3. 3.Best estimate of 625 + 405? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 44 × 72? (a) 2800 (b) 28000 (c) 280
  5. 5.Best estimate of 48 × 27? (a) 1500 (b) 15000 (c) 150
  6. 6.Best estimate of 614 + 577? (a) 1200 (b) 1400 (c) 1000
  7. 7.Best estimate of 534 + 598? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 88 × 88? (a) 81000 (b) 810 (c) 8100
  9. 9.Best estimate of 60 × 27? (a) 1800 (b) 180 (c) 18000
  10. 10.Best estimate of 71 × 57? (a) 420 (b) 42000 (c) 4200
  11. 11.Best estimate of 673 + 697? (a) 1600 (b) 1200 (c) 1400
  12. 12.Best estimate of 26 × 51? (a) 15000 (b) 1500 (c) 150
  13. 13.Best estimate of 486 + 364? (a) 1100 (b) 700 (c) 900
  14. 14.Best estimate of 348 + 637? (a) 1100 (b) 900 (c) 700
  15. 15.Best estimate of 49 × 68? (a) 350 (b) 3500 (c) 35000
  16. 16.Best estimate of 90 × 40? (a) 360 (b) 36000 (c) 3600
  17. 17.Best estimate of 76 × 49? (a) 4000 (b) 40000 (c) 400
  18. 18.Best estimate of 54 × 89? (a) 4500 (b) 45000 (c) 450
  19. 19.Best estimate of 308 + 601? (a) 1100 (b) 700 (c) 900
  20. 20.Best estimate of 877 + 208? (a) 1300 (b) 900 (c) 1100
  21. 21.Best estimate of 711 + 348? (a) 1000 (b) 1200 (c) 800
  22. 22.Best estimate of 76 × 57? (a) 48000 (b) 480 (c) 4800
  23. 23.Best estimate of 23 × 34? (a) 6000 (b) 60 (c) 600
  24. 24.Best estimate of 80 × 37? (a) 3200 (b) 32000 (c) 320
  25. 25.Best estimate of 193 + 176? (a) 400 (b) 200 (c) 600
  26. 26.Best estimate of 178 + 757? (a) 1200 (b) 800 (c) 1000
  27. 27.Best estimate of 377 + 237? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 16 × 84? (a) 160 (b) 16000 (c) 1600
  29. 29.Best estimate of 684 + 182? (a) 1100 (b) 900 (c) 700
  30. 30.Best estimate of 43 × 24? (a) 800 (b) 80 (c) 8000
  31. 31.Best estimate of 749 + 276? (a) 1000 (b) 1200 (c) 800
  32. 32.Best estimate of 16 × 86? (a) 1800 (b) 18000 (c) 180
  33. 33.Best estimate of 844 + 216? (a) 1000 (b) 1200 (c) 800
  34. 34.Best estimate of 60 × 30? (a) 180 (b) 18000 (c) 1800
  35. 35.Best estimate of 13 × 38? (a) 40 (b) 4000 (c) 400
  36. 36.Best estimate of 451 + 533? (a) 1200 (b) 800 (c) 1000
  37. 37.Best estimate of 49 × 24? (a) 1000 (b) 10000 (c) 100
  38. 38.Best estimate of 283 + 160? (a) 500 (b) 700 (c) 300
  39. 39.Best estimate of 459 + 640? (a) 1300 (b) 900 (c) 1100
  40. 40.Best estimate of 530 + 249? (a) 900 (b) 500 (c) 700

Answer key

  1. 1000
  2. 200
  3. 1000
  4. 2800
  5. 1500
  6. 1200
  7. 1100
  8. 8100
  9. 1800
  10. 4200
  11. 1400
  12. 1500
  13. 900
  14. 900
  15. 3500
  16. 3600
  17. 4000
  18. 4500
  19. 900
  20. 1100
  21. 1000
  22. 4800
  23. 600
  24. 3200
  25. 400
  26. 1000
  27. 600
  28. 1600
  29. 900
  30. 800
  31. 1000
  32. 1800
  33. 1000
  34. 1800
  35. 400
  36. 1000
  37. 1000
  38. 500
  39. 1100
  40. 700

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