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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 430 · 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 81 × 22? (a) 16000 (b) 160 (c) 1600
  2. 2.Best estimate of 21 × 42? (a) 800 (b) 80 (c) 8000
  3. 3.Best estimate of 37 × 30? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 782 + 311? (a) 900 (b) 1300 (c) 1100
  5. 5.Best estimate of 533 + 220? (a) 500 (b) 900 (c) 700
  6. 6.Best estimate of 841 + 705? (a) 1700 (b) 1300 (c) 1500
  7. 7.Best estimate of 793 + 584? (a) 1200 (b) 1600 (c) 1400
  8. 8.Best estimate of 772 + 322? (a) 1300 (b) 1100 (c) 900
  9. 9.Best estimate of 36 × 28? (a) 1200 (b) 12000 (c) 120
  10. 10.Best estimate of 339 + 439? (a) 900 (b) 500 (c) 700
  11. 11.Best estimate of 291 + 220? (a) 500 (b) 700 (c) 300
  12. 12.Best estimate of 574 + 173? (a) 800 (b) 1000 (c) 600
  13. 13.Best estimate of 76 × 61? (a) 48000 (b) 480 (c) 4800
  14. 14.Best estimate of 869 + 332? (a) 1000 (b) 1400 (c) 1200
  15. 15.Best estimate of 43 × 27? (a) 1200 (b) 12000 (c) 120
  16. 16.Best estimate of 219 + 298? (a) 500 (b) 700 (c) 300
  17. 17.Best estimate of 300 + 641? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 486 + 483? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 778 + 737? (a) 1700 (b) 1500 (c) 1300
  20. 20.Best estimate of 413 + 144? (a) 700 (b) 500 (c) 300
  21. 21.Best estimate of 456 + 289? (a) 1000 (b) 800 (c) 600
  22. 22.Best estimate of 509 + 381? (a) 1100 (b) 700 (c) 900
  23. 23.Best estimate of 70 × 16? (a) 14000 (b) 1400 (c) 140
  24. 24.Best estimate of 30 × 32? (a) 9000 (b) 90 (c) 900
  25. 25.Best estimate of 548 + 216? (a) 700 (b) 500 (c) 900
  26. 26.Best estimate of 344 + 299? (a) 600 (b) 800 (c) 400
  27. 27.Best estimate of 540 + 182? (a) 500 (b) 900 (c) 700
  28. 28.Best estimate of 50 × 82? (a) 400 (b) 4000 (c) 40000
  29. 29.Best estimate of 46 × 76? (a) 400 (b) 40000 (c) 4000
  30. 30.Best estimate of 258 + 716? (a) 1200 (b) 800 (c) 1000
  31. 31.Best estimate of 64 × 26? (a) 180 (b) 1800 (c) 18000
  32. 32.Best estimate of 159 + 711? (a) 900 (b) 700 (c) 1100
  33. 33.Best estimate of 69 × 80? (a) 560 (b) 5600 (c) 56000
  34. 34.Best estimate of 80 × 57? (a) 48000 (b) 480 (c) 4800
  35. 35.Best estimate of 326 + 714? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 394 + 852? (a) 1500 (b) 1100 (c) 1300
  37. 37.Best estimate of 261 + 768? (a) 1300 (b) 1100 (c) 900
  38. 38.Best estimate of 684 + 600? (a) 1500 (b) 1300 (c) 1100
  39. 39.Best estimate of 381 + 780? (a) 1400 (b) 1000 (c) 1200
  40. 40.Best estimate of 519 + 665? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 1600
  2. 800
  3. 1200
  4. 1100
  5. 700
  6. 1500
  7. 1400
  8. 1100
  9. 1200
  10. 700
  11. 500
  12. 800
  13. 4800
  14. 1200
  15. 1200
  16. 500
  17. 900
  18. 1000
  19. 1500
  20. 500
  21. 800
  22. 900
  23. 1400
  24. 900
  25. 700
  26. 600
  27. 700
  28. 4000
  29. 4000
  30. 1000
  31. 1800
  32. 900
  33. 5600
  34. 4800
  35. 1000
  36. 1300
  37. 1100
  38. 1300
  39. 1200
  40. 1200

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