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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 516 · 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 57 × 80? (a) 48000 (b) 4800 (c) 480
  2. 2.Best estimate of 58 × 70? (a) 42000 (b) 420 (c) 4200
  3. 3.Best estimate of 86 × 62? (a) 540 (b) 5400 (c) 54000
  4. 4.Best estimate of 644 + 182? (a) 800 (b) 1000 (c) 600
  5. 5.Best estimate of 452 + 793? (a) 1100 (b) 1500 (c) 1300
  6. 6.Best estimate of 880 + 348? (a) 1000 (b) 1400 (c) 1200
  7. 7.Best estimate of 31 × 18? (a) 600 (b) 60 (c) 6000
  8. 8.Best estimate of 21 × 48? (a) 100 (b) 10000 (c) 1000
  9. 9.Best estimate of 274 + 830? (a) 900 (b) 1100 (c) 1300
  10. 10.Best estimate of 530 + 371? (a) 900 (b) 700 (c) 1100
  11. 11.Best estimate of 66 × 66? (a) 4900 (b) 490 (c) 49000
  12. 12.Best estimate of 438 + 434? (a) 800 (b) 600 (c) 1000
  13. 13.Best estimate of 559 + 136? (a) 500 (b) 700 (c) 900
  14. 14.Best estimate of 257 + 351? (a) 900 (b) 500 (c) 700
  15. 15.Best estimate of 341 + 684? (a) 800 (b) 1000 (c) 1200
  16. 16.Best estimate of 835 + 168? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 402 + 166? (a) 600 (b) 400 (c) 800
  18. 18.Best estimate of 264 + 226? (a) 700 (b) 300 (c) 500
  19. 19.Best estimate of 831 + 561? (a) 1600 (b) 1400 (c) 1200
  20. 20.Best estimate of 18 × 86? (a) 1800 (b) 180 (c) 18000
  21. 21.Best estimate of 406 + 803? (a) 1000 (b) 1200 (c) 1400
  22. 22.Best estimate of 682 + 701? (a) 1200 (b) 1600 (c) 1400
  23. 23.Best estimate of 296 + 388? (a) 700 (b) 500 (c) 900
  24. 24.Best estimate of 23 × 39? (a) 800 (b) 8000 (c) 80
  25. 25.Best estimate of 238 + 703? (a) 900 (b) 700 (c) 1100
  26. 26.Best estimate of 537 + 213? (a) 900 (b) 700 (c) 500
  27. 27.Best estimate of 57 × 96? (a) 6000 (b) 60000 (c) 600
  28. 28.Best estimate of 28 × 86? (a) 27000 (b) 270 (c) 2700
  29. 29.Best estimate of 646 + 763? (a) 1400 (b) 1600 (c) 1200
  30. 30.Best estimate of 74 × 29? (a) 2100 (b) 210 (c) 21000
  31. 31.Best estimate of 40 × 93? (a) 36000 (b) 360 (c) 3600
  32. 32.Best estimate of 857 + 682? (a) 1600 (b) 1400 (c) 1800
  33. 33.Best estimate of 67 × 62? (a) 420 (b) 4200 (c) 42000
  34. 34.Best estimate of 155 + 443? (a) 600 (b) 400 (c) 800
  35. 35.Best estimate of 66 × 68? (a) 49000 (b) 490 (c) 4900
  36. 36.Best estimate of 378 + 195? (a) 600 (b) 800 (c) 400
  37. 37.Best estimate of 56 × 58? (a) 360 (b) 36000 (c) 3600
  38. 38.Best estimate of 58 × 64? (a) 3600 (b) 36000 (c) 360
  39. 39.Best estimate of 13 × 32? (a) 300 (b) 3000 (c) 30
  40. 40.Best estimate of 626 + 337? (a) 900 (b) 700 (c) 1100

Answer key

  1. 4800
  2. 4200
  3. 5400
  4. 800
  5. 1300
  6. 1200
  7. 600
  8. 1000
  9. 1100
  10. 900
  11. 4900
  12. 800
  13. 700
  14. 700
  15. 1000
  16. 1000
  17. 600
  18. 500
  19. 1400
  20. 1800
  21. 1200
  22. 1400
  23. 700
  24. 800
  25. 900
  26. 700
  27. 6000
  28. 2700
  29. 1400
  30. 2100
  31. 3600
  32. 1600
  33. 4200
  34. 600
  35. 4900
  36. 600
  37. 3600
  38. 3600
  39. 300
  40. 900

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