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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 52 · 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 804 + 566? (a) 1200 (b) 1600 (c) 1400
  2. 2.Best estimate of 81 × 20? (a) 1600 (b) 160 (c) 16000
  3. 3.Best estimate of 26 × 88? (a) 270 (b) 27000 (c) 2700
  4. 4.Best estimate of 18 × 46? (a) 10000 (b) 100 (c) 1000
  5. 5.Best estimate of 611 + 223? (a) 1000 (b) 600 (c) 800
  6. 6.Best estimate of 33 × 54? (a) 1500 (b) 15000 (c) 150
  7. 7.Best estimate of 377 + 498? (a) 1100 (b) 900 (c) 700
  8. 8.Best estimate of 755 + 176? (a) 800 (b) 1000 (c) 1200
  9. 9.Best estimate of 162 + 780? (a) 800 (b) 1200 (c) 1000
  10. 10.Best estimate of 76 × 16? (a) 160 (b) 1600 (c) 16000
  11. 11.Best estimate of 47 × 27? (a) 150 (b) 15000 (c) 1500
  12. 12.Best estimate of 20 × 36? (a) 80 (b) 8000 (c) 800
  13. 13.Best estimate of 719 + 627? (a) 1500 (b) 1300 (c) 1100
  14. 14.Best estimate of 696 + 638? (a) 1500 (b) 1100 (c) 1300
  15. 15.Best estimate of 579 + 354? (a) 800 (b) 1000 (c) 1200
  16. 16.Best estimate of 574 + 496? (a) 1300 (b) 1100 (c) 900
  17. 17.Best estimate of 13 × 96? (a) 100 (b) 1000 (c) 10000
  18. 18.Best estimate of 602 + 363? (a) 800 (b) 1000 (c) 1200
  19. 19.Best estimate of 622 + 533? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 797 + 806? (a) 1600 (b) 1400 (c) 1800
  21. 21.Best estimate of 251 + 134? (a) 200 (b) 600 (c) 400
  22. 22.Best estimate of 767 + 661? (a) 1700 (b) 1500 (c) 1300
  23. 23.Best estimate of 16 × 16? (a) 40 (b) 4000 (c) 400
  24. 24.Best estimate of 309 + 129? (a) 600 (b) 400 (c) 200
  25. 25.Best estimate of 791 + 211? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 185 + 509? (a) 700 (b) 900 (c) 500
  27. 27.Best estimate of 219 + 877? (a) 1100 (b) 900 (c) 1300
  28. 28.Best estimate of 50 × 78? (a) 4000 (b) 400 (c) 40000
  29. 29.Best estimate of 88 × 78? (a) 72000 (b) 720 (c) 7200
  30. 30.Best estimate of 662 + 333? (a) 800 (b) 1200 (c) 1000
  31. 31.Best estimate of 92 × 76? (a) 72000 (b) 720 (c) 7200
  32. 32.Best estimate of 19 × 57? (a) 120 (b) 1200 (c) 12000
  33. 33.Best estimate of 40 × 93? (a) 36000 (b) 3600 (c) 360
  34. 34.Best estimate of 89 × 39? (a) 360 (b) 3600 (c) 36000
  35. 35.Best estimate of 74 × 81? (a) 5600 (b) 560 (c) 56000
  36. 36.Best estimate of 565 + 139? (a) 900 (b) 700 (c) 500
  37. 37.Best estimate of 56 × 52? (a) 3000 (b) 30000 (c) 300
  38. 38.Best estimate of 66 × 84? (a) 5600 (b) 560 (c) 56000
  39. 39.Best estimate of 30 × 62? (a) 1800 (b) 18000 (c) 180
  40. 40.Best estimate of 122 + 709? (a) 1000 (b) 800 (c) 600

Answer key

  1. 1400
  2. 1600
  3. 2700
  4. 1000
  5. 800
  6. 1500
  7. 900
  8. 1000
  9. 1000
  10. 1600
  11. 1500
  12. 800
  13. 1300
  14. 1300
  15. 1000
  16. 1100
  17. 1000
  18. 1000
  19. 1100
  20. 1600
  21. 400
  22. 1500
  23. 400
  24. 400
  25. 1000
  26. 700
  27. 1100
  28. 4000
  29. 7200
  30. 1000
  31. 7200
  32. 1200
  33. 3600
  34. 3600
  35. 5600
  36. 700
  37. 3000
  38. 5600
  39. 1800
  40. 800

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