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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 951 · 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 216 + 277? (a) 700 (b) 500 (c) 300
  2. 2.Best estimate of 366 + 155? (a) 800 (b) 600 (c) 400
  3. 3.Best estimate of 74 × 50? (a) 350 (b) 35000 (c) 3500
  4. 4.Best estimate of 515 + 323? (a) 1000 (b) 600 (c) 800
  5. 5.Best estimate of 164 + 408? (a) 600 (b) 800 (c) 400
  6. 6.Best estimate of 23 × 76? (a) 160 (b) 1600 (c) 16000
  7. 7.Best estimate of 538 + 717? (a) 1400 (b) 1200 (c) 1000
  8. 8.Best estimate of 44 × 49? (a) 20000 (b) 200 (c) 2000
  9. 9.Best estimate of 120 + 441? (a) 300 (b) 500 (c) 700
  10. 10.Best estimate of 808 + 480? (a) 1300 (b) 1100 (c) 1500
  11. 11.Best estimate of 17 × 41? (a) 80 (b) 8000 (c) 800
  12. 12.Best estimate of 59 × 72? (a) 4200 (b) 42000 (c) 420
  13. 13.Best estimate of 28 × 40? (a) 12000 (b) 120 (c) 1200
  14. 14.Best estimate of 219 + 428? (a) 600 (b) 400 (c) 800
  15. 15.Best estimate of 70 × 96? (a) 700 (b) 70000 (c) 7000
  16. 16.Best estimate of 720 + 475? (a) 1200 (b) 1000 (c) 1400
  17. 17.Best estimate of 82 × 96? (a) 80000 (b) 8000 (c) 800
  18. 18.Best estimate of 823 + 274? (a) 1300 (b) 1100 (c) 900
  19. 19.Best estimate of 49 × 42? (a) 2000 (b) 20000 (c) 200
  20. 20.Best estimate of 323 + 703? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 66 × 27? (a) 21000 (b) 210 (c) 2100
  22. 22.Best estimate of 601 + 269? (a) 900 (b) 1100 (c) 700
  23. 23.Best estimate of 274 + 636? (a) 1100 (b) 700 (c) 900
  24. 24.Best estimate of 56 × 77? (a) 48000 (b) 480 (c) 4800
  25. 25.Best estimate of 56 × 50? (a) 3000 (b) 30000 (c) 300
  26. 26.Best estimate of 51 × 76? (a) 4000 (b) 40000 (c) 400
  27. 27.Best estimate of 845 + 282? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 34 × 56? (a) 1800 (b) 18000 (c) 180
  29. 29.Best estimate of 637 + 871? (a) 1700 (b) 1500 (c) 1300
  30. 30.Best estimate of 360 + 808? (a) 1200 (b) 1000 (c) 1400
  31. 31.Best estimate of 96 × 52? (a) 5000 (b) 50000 (c) 500
  32. 32.Best estimate of 122 + 535? (a) 800 (b) 400 (c) 600
  33. 33.Best estimate of 804 + 139? (a) 900 (b) 700 (c) 1100
  34. 34.Best estimate of 68 × 48? (a) 3500 (b) 350 (c) 35000
  35. 35.Best estimate of 39 × 64? (a) 2400 (b) 240 (c) 24000
  36. 36.Best estimate of 21 × 48? (a) 10000 (b) 100 (c) 1000
  37. 37.Best estimate of 33 × 64? (a) 1800 (b) 180 (c) 18000
  38. 38.Best estimate of 16 × 24? (a) 4000 (b) 400 (c) 40
  39. 39.Best estimate of 714 + 287? (a) 1000 (b) 1200 (c) 800
  40. 40.Best estimate of 227 + 449? (a) 400 (b) 600 (c) 800

Answer key

  1. 500
  2. 600
  3. 3500
  4. 800
  5. 600
  6. 1600
  7. 1200
  8. 2000
  9. 500
  10. 1300
  11. 800
  12. 4200
  13. 1200
  14. 600
  15. 7000
  16. 1200
  17. 8000
  18. 1100
  19. 2000
  20. 1000
  21. 2100
  22. 900
  23. 900
  24. 4800
  25. 3000
  26. 4000
  27. 1100
  28. 1800
  29. 1500
  30. 1200
  31. 5000
  32. 600
  33. 900
  34. 3500
  35. 2400
  36. 1000
  37. 1800
  38. 400
  39. 1000
  40. 600

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