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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 911 · 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 68 × 38? (a) 2800 (b) 28000 (c) 280
  2. 2.Best estimate of 72 × 34? (a) 2100 (b) 21000 (c) 210
  3. 3.Best estimate of 831 + 264? (a) 1300 (b) 1100 (c) 900
  4. 4.Best estimate of 66 × 52? (a) 35000 (b) 350 (c) 3500
  5. 5.Best estimate of 63 × 76? (a) 480 (b) 48000 (c) 4800
  6. 6.Best estimate of 280 + 811? (a) 1300 (b) 1100 (c) 900
  7. 7.Best estimate of 93 × 72? (a) 63000 (b) 6300 (c) 630
  8. 8.Best estimate of 426 + 800? (a) 1200 (b) 1000 (c) 1400
  9. 9.Best estimate of 198 + 200? (a) 400 (b) 200 (c) 600
  10. 10.Best estimate of 138 + 869? (a) 1200 (b) 800 (c) 1000
  11. 11.Best estimate of 823 + 155? (a) 1000 (b) 800 (c) 1200
  12. 12.Best estimate of 62 × 93? (a) 54000 (b) 540 (c) 5400
  13. 13.Best estimate of 227 + 186? (a) 400 (b) 200 (c) 600
  14. 14.Best estimate of 611 + 688? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 39 × 43? (a) 1600 (b) 160 (c) 16000
  16. 16.Best estimate of 93 × 26? (a) 2700 (b) 270 (c) 27000
  17. 17.Best estimate of 50 × 79? (a) 40000 (b) 400 (c) 4000
  18. 18.Best estimate of 39 × 41? (a) 1600 (b) 160 (c) 16000
  19. 19.Best estimate of 31 × 28? (a) 9000 (b) 900 (c) 90
  20. 20.Best estimate of 32 × 62? (a) 180 (b) 1800 (c) 18000
  21. 21.Best estimate of 861 + 721? (a) 1600 (b) 1400 (c) 1800
  22. 22.Best estimate of 56 × 31? (a) 180 (b) 18000 (c) 1800
  23. 23.Best estimate of 13 × 21? (a) 200 (b) 20 (c) 2000
  24. 24.Best estimate of 690 + 576? (a) 1300 (b) 1500 (c) 1100
  25. 25.Best estimate of 804 + 388? (a) 1200 (b) 1400 (c) 1000
  26. 26.Best estimate of 272 + 853? (a) 1400 (b) 1000 (c) 1200
  27. 27.Best estimate of 30 × 83? (a) 240 (b) 24000 (c) 2400
  28. 28.Best estimate of 567 + 771? (a) 1600 (b) 1400 (c) 1200
  29. 29.Best estimate of 878 + 240? (a) 1100 (b) 1300 (c) 900
  30. 30.Best estimate of 27 × 30? (a) 9000 (b) 90 (c) 900
  31. 31.Best estimate of 531 + 159? (a) 500 (b) 700 (c) 900
  32. 32.Best estimate of 153 + 752? (a) 800 (b) 1200 (c) 1000
  33. 33.Best estimate of 98 × 26? (a) 30000 (b) 300 (c) 3000
  34. 34.Best estimate of 51 × 44? (a) 2000 (b) 20000 (c) 200
  35. 35.Best estimate of 48 × 72? (a) 3500 (b) 350 (c) 35000
  36. 36.Best estimate of 34 × 54? (a) 15000 (b) 1500 (c) 150
  37. 37.Best estimate of 456 + 780? (a) 1100 (b) 1300 (c) 1500
  38. 38.Best estimate of 80 × 94? (a) 72000 (b) 7200 (c) 720
  39. 39.Best estimate of 810 + 835? (a) 1600 (b) 1800 (c) 1400
  40. 40.Best estimate of 620 + 194? (a) 600 (b) 1000 (c) 800

Answer key

  1. 2800
  2. 2100
  3. 1100
  4. 3500
  5. 4800
  6. 1100
  7. 6300
  8. 1200
  9. 400
  10. 1000
  11. 1000
  12. 5400
  13. 400
  14. 1300
  15. 1600
  16. 2700
  17. 4000
  18. 1600
  19. 900
  20. 1800
  21. 1600
  22. 1800
  23. 200
  24. 1300
  25. 1200
  26. 1200
  27. 2400
  28. 1400
  29. 1100
  30. 900
  31. 700
  32. 1000
  33. 3000
  34. 2000
  35. 3500
  36. 1500
  37. 1300
  38. 7200
  39. 1600
  40. 800

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