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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 768 · 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 406 + 486? (a) 900 (b) 700 (c) 1100
  2. 2.Best estimate of 17 × 69? (a) 140 (b) 14000 (c) 1400
  3. 3.Best estimate of 26 × 50? (a) 150 (b) 1500 (c) 15000
  4. 4.Best estimate of 44 × 16? (a) 8000 (b) 800 (c) 80
  5. 5.Best estimate of 51 × 78? (a) 400 (b) 40000 (c) 4000
  6. 6.Best estimate of 61 × 78? (a) 480 (b) 4800 (c) 48000
  7. 7.Best estimate of 508 + 673? (a) 1400 (b) 1200 (c) 1000
  8. 8.Best estimate of 828 + 757? (a) 1800 (b) 1400 (c) 1600
  9. 9.Best estimate of 72 × 39? (a) 28000 (b) 2800 (c) 280
  10. 10.Best estimate of 44 × 62? (a) 240 (b) 2400 (c) 24000
  11. 11.Best estimate of 73 × 96? (a) 700 (b) 7000 (c) 70000
  12. 12.Best estimate of 504 + 501? (a) 800 (b) 1200 (c) 1000
  13. 13.Best estimate of 66 × 86? (a) 630 (b) 6300 (c) 63000
  14. 14.Best estimate of 73 × 26? (a) 21000 (b) 2100 (c) 210
  15. 15.Best estimate of 285 + 137? (a) 600 (b) 200 (c) 400
  16. 16.Best estimate of 842 + 248? (a) 1000 (b) 800 (c) 1200
  17. 17.Best estimate of 82 × 46? (a) 4000 (b) 40000 (c) 400
  18. 18.Best estimate of 506 + 839? (a) 1500 (b) 1300 (c) 1100
  19. 19.Best estimate of 67 × 14? (a) 7000 (b) 700 (c) 70
  20. 20.Best estimate of 31 × 16? (a) 600 (b) 60 (c) 6000
  21. 21.Best estimate of 241 + 391? (a) 800 (b) 600 (c) 400
  22. 22.Best estimate of 800 + 300? (a) 1300 (b) 1100 (c) 900
  23. 23.Best estimate of 839 + 375? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 397 + 271? (a) 900 (b) 700 (c) 500
  25. 25.Best estimate of 64 × 53? (a) 3000 (b) 300 (c) 30000
  26. 26.Best estimate of 365 + 266? (a) 500 (b) 700 (c) 900
  27. 27.Best estimate of 349 + 557? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 326 + 440? (a) 900 (b) 500 (c) 700
  29. 29.Best estimate of 97 × 26? (a) 3000 (b) 30000 (c) 300
  30. 30.Best estimate of 91 × 52? (a) 450 (b) 4500 (c) 45000
  31. 31.Best estimate of 61 × 46? (a) 3000 (b) 30000 (c) 300
  32. 32.Best estimate of 91 × 31? (a) 2700 (b) 270 (c) 27000
  33. 33.Best estimate of 74 × 18? (a) 140 (b) 1400 (c) 14000
  34. 34.Best estimate of 38 × 13? (a) 40 (b) 4000 (c) 400
  35. 35.Best estimate of 335 + 414? (a) 700 (b) 500 (c) 900
  36. 36.Best estimate of 133 + 182? (a) 300 (b) 100 (c) 500
  37. 37.Best estimate of 79 × 57? (a) 48000 (b) 480 (c) 4800
  38. 38.Best estimate of 615 + 242? (a) 800 (b) 600 (c) 1000
  39. 39.Best estimate of 69 × 52? (a) 35000 (b) 3500 (c) 350
  40. 40.Best estimate of 29 × 74? (a) 2100 (b) 210 (c) 21000

Answer key

  1. 900
  2. 1400
  3. 1500
  4. 800
  5. 4000
  6. 4800
  7. 1200
  8. 1600
  9. 2800
  10. 2400
  11. 7000
  12. 1000
  13. 6300
  14. 2100
  15. 400
  16. 1000
  17. 4000
  18. 1300
  19. 700
  20. 600
  21. 600
  22. 1100
  23. 1200
  24. 700
  25. 3000
  26. 700
  27. 900
  28. 700
  29. 3000
  30. 4500
  31. 3000
  32. 2700
  33. 1400
  34. 400
  35. 700
  36. 300
  37. 4800
  38. 800
  39. 3500
  40. 2100

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