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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 447 · 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 580 + 641? (a) 1200 (b) 1000 (c) 1400
  2. 2.Best estimate of 457 + 333? (a) 800 (b) 600 (c) 1000
  3. 3.Best estimate of 94 × 43? (a) 360 (b) 3600 (c) 36000
  4. 4.Best estimate of 81 × 47? (a) 400 (b) 4000 (c) 40000
  5. 5.Best estimate of 717 + 486? (a) 1400 (b) 1200 (c) 1000
  6. 6.Best estimate of 16 × 67? (a) 14000 (b) 1400 (c) 140
  7. 7.Best estimate of 67 × 73? (a) 49000 (b) 490 (c) 4900
  8. 8.Best estimate of 819 + 433? (a) 1000 (b) 1400 (c) 1200
  9. 9.Best estimate of 418 + 179? (a) 600 (b) 800 (c) 400
  10. 10.Best estimate of 43 × 92? (a) 36000 (b) 3600 (c) 360
  11. 11.Best estimate of 90 × 50? (a) 45000 (b) 4500 (c) 450
  12. 12.Best estimate of 80 × 82? (a) 640 (b) 64000 (c) 6400
  13. 13.Best estimate of 693 + 126? (a) 600 (b) 800 (c) 1000
  14. 14.Best estimate of 96 × 18? (a) 20000 (b) 2000 (c) 200
  15. 15.Best estimate of 859 + 179? (a) 1100 (b) 900 (c) 1300
  16. 16.Best estimate of 321 + 373? (a) 700 (b) 500 (c) 900
  17. 17.Best estimate of 56 × 97? (a) 60000 (b) 600 (c) 6000
  18. 18.Best estimate of 26 × 36? (a) 1200 (b) 12000 (c) 120
  19. 19.Best estimate of 220 + 604? (a) 800 (b) 1000 (c) 600
  20. 20.Best estimate of 554 + 131? (a) 900 (b) 700 (c) 500
  21. 21.Best estimate of 72 × 22? (a) 140 (b) 1400 (c) 14000
  22. 22.Best estimate of 191 + 653? (a) 900 (b) 700 (c) 1100
  23. 23.Best estimate of 44 × 28? (a) 1200 (b) 120 (c) 12000
  24. 24.Best estimate of 32 × 26? (a) 900 (b) 9000 (c) 90
  25. 25.Best estimate of 19 × 51? (a) 100 (b) 10000 (c) 1000
  26. 26.Best estimate of 523 + 864? (a) 1600 (b) 1400 (c) 1200
  27. 27.Best estimate of 21 × 38? (a) 8000 (b) 800 (c) 80
  28. 28.Best estimate of 64 × 33? (a) 1800 (b) 180 (c) 18000
  29. 29.Best estimate of 325 + 655? (a) 800 (b) 1000 (c) 1200
  30. 30.Best estimate of 428 + 456? (a) 1100 (b) 900 (c) 700
  31. 31.Best estimate of 30 × 44? (a) 120 (b) 12000 (c) 1200
  32. 32.Best estimate of 37 × 48? (a) 2000 (b) 20000 (c) 200
  33. 33.Best estimate of 59 × 26? (a) 1800 (b) 18000 (c) 180
  34. 34.Best estimate of 91 × 91? (a) 81000 (b) 810 (c) 8100
  35. 35.Best estimate of 569 + 311? (a) 700 (b) 1100 (c) 900
  36. 36.Best estimate of 78 × 94? (a) 72000 (b) 720 (c) 7200
  37. 37.Best estimate of 806 + 232? (a) 1200 (b) 800 (c) 1000
  38. 38.Best estimate of 264 + 531? (a) 800 (b) 600 (c) 1000
  39. 39.Best estimate of 62 × 54? (a) 300 (b) 3000 (c) 30000
  40. 40.Best estimate of 51 × 46? (a) 25000 (b) 2500 (c) 250

Answer key

  1. 1200
  2. 800
  3. 3600
  4. 4000
  5. 1200
  6. 1400
  7. 4900
  8. 1200
  9. 600
  10. 3600
  11. 4500
  12. 6400
  13. 800
  14. 2000
  15. 1100
  16. 700
  17. 6000
  18. 1200
  19. 800
  20. 700
  21. 1400
  22. 900
  23. 1200
  24. 900
  25. 1000
  26. 1400
  27. 800
  28. 1800
  29. 1000
  30. 900
  31. 1200
  32. 2000
  33. 1800
  34. 8100
  35. 900
  36. 7200
  37. 1000
  38. 800
  39. 3000
  40. 2500

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