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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 924 · 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 20 × 32? (a) 600 (b) 6000 (c) 60
  2. 2.Best estimate of 88 × 13? (a) 9000 (b) 90 (c) 900
  3. 3.Best estimate of 641 + 361? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 724 + 241? (a) 700 (b) 1100 (c) 900
  5. 5.Best estimate of 866 + 282? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 441 + 768? (a) 1200 (b) 1000 (c) 1400
  7. 7.Best estimate of 93 × 26? (a) 270 (b) 27000 (c) 2700
  8. 8.Best estimate of 16 × 16? (a) 4000 (b) 40 (c) 400
  9. 9.Best estimate of 50 × 87? (a) 450 (b) 4500 (c) 45000
  10. 10.Best estimate of 364 + 291? (a) 700 (b) 500 (c) 900
  11. 11.Best estimate of 16 × 23? (a) 4000 (b) 400 (c) 40
  12. 12.Best estimate of 40 × 17? (a) 800 (b) 80 (c) 8000
  13. 13.Best estimate of 807 + 836? (a) 1600 (b) 1800 (c) 1400
  14. 14.Best estimate of 455 + 570? (a) 1300 (b) 900 (c) 1100
  15. 15.Best estimate of 308 + 343? (a) 800 (b) 400 (c) 600
  16. 16.Best estimate of 51 × 56? (a) 3000 (b) 30000 (c) 300
  17. 17.Best estimate of 477 + 231? (a) 500 (b) 700 (c) 900
  18. 18.Best estimate of 43 × 67? (a) 280 (b) 2800 (c) 28000
  19. 19.Best estimate of 177 + 712? (a) 900 (b) 700 (c) 1100
  20. 20.Best estimate of 764 + 477? (a) 1100 (b) 1500 (c) 1300
  21. 21.Best estimate of 37 × 81? (a) 3200 (b) 320 (c) 32000
  22. 22.Best estimate of 67 × 40? (a) 280 (b) 28000 (c) 2800
  23. 23.Best estimate of 40 × 13? (a) 4000 (b) 40 (c) 400
  24. 24.Best estimate of 58 × 70? (a) 420 (b) 4200 (c) 42000
  25. 25.Best estimate of 738 + 280? (a) 1000 (b) 1200 (c) 800
  26. 26.Best estimate of 59 × 56? (a) 3600 (b) 36000 (c) 360
  27. 27.Best estimate of 76 × 96? (a) 8000 (b) 800 (c) 80000
  28. 28.Best estimate of 28 × 59? (a) 18000 (b) 180 (c) 1800
  29. 29.Best estimate of 62 × 80? (a) 480 (b) 4800 (c) 48000
  30. 30.Best estimate of 629 + 747? (a) 1300 (b) 1100 (c) 1500
  31. 31.Best estimate of 21 × 21? (a) 400 (b) 40 (c) 4000
  32. 32.Best estimate of 843 + 180? (a) 1200 (b) 1000 (c) 800
  33. 33.Best estimate of 153 + 265? (a) 500 (b) 300 (c) 700
  34. 34.Best estimate of 301 + 211? (a) 500 (b) 300 (c) 700
  35. 35.Best estimate of 41 × 21? (a) 800 (b) 8000 (c) 80
  36. 36.Best estimate of 316 + 421? (a) 900 (b) 500 (c) 700
  37. 37.Best estimate of 805 + 246? (a) 1200 (b) 1000 (c) 800
  38. 38.Best estimate of 16 × 48? (a) 10000 (b) 100 (c) 1000
  39. 39.Best estimate of 220 + 297? (a) 500 (b) 300 (c) 700
  40. 40.Best estimate of 38 × 40? (a) 1600 (b) 16000 (c) 160

Answer key

  1. 600
  2. 900
  3. 1000
  4. 900
  5. 1200
  6. 1200
  7. 2700
  8. 400
  9. 4500
  10. 700
  11. 400
  12. 800
  13. 1600
  14. 1100
  15. 600
  16. 3000
  17. 700
  18. 2800
  19. 900
  20. 1300
  21. 3200
  22. 2800
  23. 400
  24. 4200
  25. 1000
  26. 3600
  27. 8000
  28. 1800
  29. 4800
  30. 1300
  31. 400
  32. 1000
  33. 500
  34. 500
  35. 800
  36. 700
  37. 1000
  38. 1000
  39. 500
  40. 1600

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