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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 314 · 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 861 + 284? (a) 1400 (b) 1000 (c) 1200
  2. 2.Best estimate of 92 × 21? (a) 180 (b) 18000 (c) 1800
  3. 3.Best estimate of 839 + 545? (a) 1500 (b) 1300 (c) 1100
  4. 4.Best estimate of 38 × 53? (a) 20000 (b) 200 (c) 2000
  5. 5.Best estimate of 36 × 72? (a) 28000 (b) 280 (c) 2800
  6. 6.Best estimate of 838 + 212? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 788 + 697? (a) 1300 (b) 1500 (c) 1700
  8. 8.Best estimate of 587 + 596? (a) 1200 (b) 1400 (c) 1000
  9. 9.Best estimate of 485 + 189? (a) 700 (b) 900 (c) 500
  10. 10.Best estimate of 274 + 593? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 731 + 387? (a) 1300 (b) 900 (c) 1100
  12. 12.Best estimate of 329 + 799? (a) 900 (b) 1300 (c) 1100
  13. 13.Best estimate of 30 × 38? (a) 120 (b) 1200 (c) 12000
  14. 14.Best estimate of 870 + 845? (a) 1700 (b) 1900 (c) 1500
  15. 15.Best estimate of 80 × 91? (a) 7200 (b) 720 (c) 72000
  16. 16.Best estimate of 133 + 196? (a) 500 (b) 100 (c) 300
  17. 17.Best estimate of 76 × 73? (a) 5600 (b) 560 (c) 56000
  18. 18.Best estimate of 734 + 702? (a) 1400 (b) 1600 (c) 1200
  19. 19.Best estimate of 62 × 81? (a) 48000 (b) 480 (c) 4800
  20. 20.Best estimate of 781 + 120? (a) 900 (b) 1100 (c) 700
  21. 21.Best estimate of 46 × 37? (a) 2000 (b) 200 (c) 20000
  22. 22.Best estimate of 836 + 822? (a) 1600 (b) 1800 (c) 1400
  23. 23.Best estimate of 56 × 32? (a) 18000 (b) 180 (c) 1800
  24. 24.Best estimate of 19 × 12? (a) 2000 (b) 200 (c) 20
  25. 25.Best estimate of 21 × 30? (a) 600 (b) 6000 (c) 60
  26. 26.Best estimate of 834 + 705? (a) 1300 (b) 1700 (c) 1500
  27. 27.Best estimate of 627 + 342? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 36 × 30? (a) 1200 (b) 120 (c) 12000
  29. 29.Best estimate of 17 × 96? (a) 200 (b) 2000 (c) 20000
  30. 30.Best estimate of 68 × 26? (a) 21000 (b) 210 (c) 2100
  31. 31.Best estimate of 47 × 21? (a) 1000 (b) 100 (c) 10000
  32. 32.Best estimate of 26 × 29? (a) 900 (b) 9000 (c) 90
  33. 33.Best estimate of 37 × 31? (a) 12000 (b) 1200 (c) 120
  34. 34.Best estimate of 33 × 90? (a) 27000 (b) 270 (c) 2700
  35. 35.Best estimate of 249 + 378? (a) 600 (b) 800 (c) 400
  36. 36.Best estimate of 739 + 123? (a) 1000 (b) 800 (c) 600
  37. 37.Best estimate of 269 + 634? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 146 + 124? (a) 0 (b) 200 (c) 400
  39. 39.Best estimate of 757 + 664? (a) 1700 (b) 1500 (c) 1300
  40. 40.Best estimate of 24 × 89? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 1200
  2. 1800
  3. 1300
  4. 2000
  5. 2800
  6. 1000
  7. 1500
  8. 1200
  9. 700
  10. 900
  11. 1100
  12. 1100
  13. 1200
  14. 1700
  15. 7200
  16. 300
  17. 5600
  18. 1400
  19. 4800
  20. 900
  21. 2000
  22. 1600
  23. 1800
  24. 200
  25. 600
  26. 1500
  27. 900
  28. 1200
  29. 2000
  30. 2100
  31. 1000
  32. 900
  33. 1200
  34. 2700
  35. 600
  36. 800
  37. 900
  38. 200
  39. 1500
  40. 1800

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