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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 161 · 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 84 × 63? (a) 480 (b) 4800 (c) 48000
  2. 2.Best estimate of 139 + 641? (a) 700 (b) 900 (c) 500
  3. 3.Best estimate of 78 × 97? (a) 80000 (b) 800 (c) 8000
  4. 4.Best estimate of 296 + 869? (a) 1200 (b) 1400 (c) 1000
  5. 5.Best estimate of 143 + 219? (a) 500 (b) 100 (c) 300
  6. 6.Best estimate of 123 + 377? (a) 700 (b) 300 (c) 500
  7. 7.Best estimate of 302 + 289? (a) 800 (b) 400 (c) 600
  8. 8.Best estimate of 28 × 36? (a) 12000 (b) 1200 (c) 120
  9. 9.Best estimate of 515 + 539? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 57 × 27? (a) 1800 (b) 180 (c) 18000
  11. 11.Best estimate of 876 + 732? (a) 1400 (b) 1800 (c) 1600
  12. 12.Best estimate of 17 × 90? (a) 180 (b) 18000 (c) 1800
  13. 13.Best estimate of 26 × 46? (a) 1500 (b) 15000 (c) 150
  14. 14.Best estimate of 241 + 667? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 588 + 707? (a) 1100 (b) 1500 (c) 1300
  16. 16.Best estimate of 653 + 666? (a) 1600 (b) 1200 (c) 1400
  17. 17.Best estimate of 77 × 12? (a) 800 (b) 8000 (c) 80
  18. 18.Best estimate of 70 × 53? (a) 35000 (b) 3500 (c) 350
  19. 19.Best estimate of 36 × 38? (a) 16000 (b) 1600 (c) 160
  20. 20.Best estimate of 835 + 823? (a) 1800 (b) 1600 (c) 1400
  21. 21.Best estimate of 36 × 20? (a) 80 (b) 800 (c) 8000
  22. 22.Best estimate of 226 + 444? (a) 800 (b) 600 (c) 400
  23. 23.Best estimate of 352 + 784? (a) 1400 (b) 1000 (c) 1200
  24. 24.Best estimate of 784 + 835? (a) 1600 (b) 1800 (c) 1400
  25. 25.Best estimate of 851 + 533? (a) 1600 (b) 1200 (c) 1400
  26. 26.Best estimate of 353 + 532? (a) 900 (b) 700 (c) 1100
  27. 27.Best estimate of 574 + 328? (a) 700 (b) 900 (c) 1100
  28. 28.Best estimate of 97 × 40? (a) 400 (b) 4000 (c) 40000
  29. 29.Best estimate of 48 × 26? (a) 1500 (b) 150 (c) 15000
  30. 30.Best estimate of 851 + 815? (a) 1500 (b) 1900 (c) 1700
  31. 31.Best estimate of 720 + 468? (a) 1200 (b) 1000 (c) 1400
  32. 32.Best estimate of 219 + 748? (a) 900 (b) 1100 (c) 700
  33. 33.Best estimate of 49 × 37? (a) 20000 (b) 200 (c) 2000
  34. 34.Best estimate of 90 × 16? (a) 1800 (b) 18000 (c) 180
  35. 35.Best estimate of 624 + 228? (a) 800 (b) 1000 (c) 600
  36. 36.Best estimate of 870 + 794? (a) 1700 (b) 1900 (c) 1500
  37. 37.Best estimate of 73 × 46? (a) 35000 (b) 350 (c) 3500
  38. 38.Best estimate of 86 × 83? (a) 7200 (b) 72000 (c) 720
  39. 39.Best estimate of 26 × 62? (a) 18000 (b) 180 (c) 1800
  40. 40.Best estimate of 422 + 554? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 4800
  2. 700
  3. 8000
  4. 1200
  5. 300
  6. 500
  7. 600
  8. 1200
  9. 1000
  10. 1800
  11. 1600
  12. 1800
  13. 1500
  14. 900
  15. 1300
  16. 1400
  17. 800
  18. 3500
  19. 1600
  20. 1600
  21. 800
  22. 600
  23. 1200
  24. 1600
  25. 1400
  26. 900
  27. 900
  28. 4000
  29. 1500
  30. 1700
  31. 1200
  32. 900
  33. 2000
  34. 1800
  35. 800
  36. 1700
  37. 3500
  38. 7200
  39. 1800
  40. 1000

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