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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 169 · 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 59 × 61? (a) 360 (b) 3600 (c) 36000
  2. 2.Best estimate of 28 × 86? (a) 270 (b) 2700 (c) 27000
  3. 3.Best estimate of 38 × 56? (a) 24000 (b) 240 (c) 2400
  4. 4.Best estimate of 36 × 57? (a) 240 (b) 2400 (c) 24000
  5. 5.Best estimate of 196 + 299? (a) 300 (b) 500 (c) 700
  6. 6.Best estimate of 214 + 389? (a) 600 (b) 800 (c) 400
  7. 7.Best estimate of 36 × 41? (a) 1600 (b) 16000 (c) 160
  8. 8.Best estimate of 313 + 462? (a) 1000 (b) 800 (c) 600
  9. 9.Best estimate of 52 × 80? (a) 400 (b) 4000 (c) 40000
  10. 10.Best estimate of 552 + 599? (a) 1400 (b) 1200 (c) 1000
  11. 11.Best estimate of 36 × 17? (a) 80 (b) 800 (c) 8000
  12. 12.Best estimate of 71 × 66? (a) 4900 (b) 490 (c) 49000
  13. 13.Best estimate of 243 + 143? (a) 100 (b) 500 (c) 300
  14. 14.Best estimate of 644 + 753? (a) 1400 (b) 1600 (c) 1200
  15. 15.Best estimate of 586 + 259? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 31 × 19? (a) 6000 (b) 600 (c) 60
  17. 17.Best estimate of 42 × 68? (a) 28000 (b) 2800 (c) 280
  18. 18.Best estimate of 22 × 52? (a) 10000 (b) 1000 (c) 100
  19. 19.Best estimate of 26 × 88? (a) 2700 (b) 270 (c) 27000
  20. 20.Best estimate of 70 × 62? (a) 4200 (b) 42000 (c) 420
  21. 21.Best estimate of 873 + 744? (a) 1800 (b) 1600 (c) 1400
  22. 22.Best estimate of 683 + 839? (a) 1500 (b) 1300 (c) 1700
  23. 23.Best estimate of 76 × 27? (a) 2400 (b) 240 (c) 24000
  24. 24.Best estimate of 303 + 416? (a) 700 (b) 500 (c) 900
  25. 25.Best estimate of 14 × 38? (a) 400 (b) 40 (c) 4000
  26. 26.Best estimate of 751 + 135? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 39 × 46? (a) 2000 (b) 200 (c) 20000
  28. 28.Best estimate of 93 × 24? (a) 1800 (b) 18000 (c) 180
  29. 29.Best estimate of 633 + 443? (a) 800 (b) 1200 (c) 1000
  30. 30.Best estimate of 72 × 16? (a) 140 (b) 14000 (c) 1400
  31. 31.Best estimate of 374 + 282? (a) 700 (b) 900 (c) 500
  32. 32.Best estimate of 561 + 202? (a) 600 (b) 800 (c) 1000
  33. 33.Best estimate of 46 × 88? (a) 450 (b) 45000 (c) 4500
  34. 34.Best estimate of 309 + 235? (a) 500 (b) 300 (c) 700
  35. 35.Best estimate of 863 + 280? (a) 1200 (b) 1000 (c) 1400
  36. 36.Best estimate of 494 + 374? (a) 1100 (b) 900 (c) 700
  37. 37.Best estimate of 433 + 313? (a) 700 (b) 500 (c) 900
  38. 38.Best estimate of 155 + 548? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 79 × 76? (a) 6400 (b) 64000 (c) 640
  40. 40.Best estimate of 29 × 93? (a) 27000 (b) 270 (c) 2700

Answer key

  1. 3600
  2. 2700
  3. 2400
  4. 2400
  5. 500
  6. 600
  7. 1600
  8. 800
  9. 4000
  10. 1200
  11. 800
  12. 4900
  13. 300
  14. 1400
  15. 900
  16. 600
  17. 2800
  18. 1000
  19. 2700
  20. 4200
  21. 1600
  22. 1500
  23. 2400
  24. 700
  25. 400
  26. 900
  27. 2000
  28. 1800
  29. 1000
  30. 1400
  31. 700
  32. 800
  33. 4500
  34. 500
  35. 1200
  36. 900
  37. 700
  38. 700
  39. 6400
  40. 2700

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