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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 352 · 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 86 × 33? (a) 270 (b) 27000 (c) 2700
  2. 2.Best estimate of 61 × 70? (a) 42000 (b) 420 (c) 4200
  3. 3.Best estimate of 41 × 63? (a) 2400 (b) 24000 (c) 240
  4. 4.Best estimate of 64 × 60? (a) 36000 (b) 3600 (c) 360
  5. 5.Best estimate of 701 + 441? (a) 1100 (b) 900 (c) 1300
  6. 6.Best estimate of 148 + 361? (a) 500 (b) 300 (c) 700
  7. 7.Best estimate of 76 × 30? (a) 24000 (b) 2400 (c) 240
  8. 8.Best estimate of 414 + 489? (a) 700 (b) 900 (c) 1100
  9. 9.Best estimate of 137 + 397? (a) 700 (b) 500 (c) 300
  10. 10.Best estimate of 861 + 272? (a) 1200 (b) 1000 (c) 1400
  11. 11.Best estimate of 404 + 624? (a) 1200 (b) 1000 (c) 800
  12. 12.Best estimate of 26 × 37? (a) 12000 (b) 120 (c) 1200
  13. 13.Best estimate of 826 + 756? (a) 1600 (b) 1400 (c) 1800
  14. 14.Best estimate of 56 × 80? (a) 4800 (b) 48000 (c) 480
  15. 15.Best estimate of 51 × 27? (a) 1500 (b) 150 (c) 15000
  16. 16.Best estimate of 18 × 91? (a) 18000 (b) 180 (c) 1800
  17. 17.Best estimate of 34 × 19? (a) 600 (b) 60 (c) 6000
  18. 18.Best estimate of 867 + 483? (a) 1200 (b) 1400 (c) 1600
  19. 19.Best estimate of 36 × 72? (a) 2800 (b) 28000 (c) 280
  20. 20.Best estimate of 670 + 202? (a) 1100 (b) 700 (c) 900
  21. 21.Best estimate of 209 + 829? (a) 1200 (b) 1000 (c) 800
  22. 22.Best estimate of 97 × 13? (a) 1000 (b) 10000 (c) 100
  23. 23.Best estimate of 323 + 721? (a) 1200 (b) 800 (c) 1000
  24. 24.Best estimate of 23 × 22? (a) 40 (b) 400 (c) 4000
  25. 25.Best estimate of 695 + 729? (a) 1600 (b) 1400 (c) 1200
  26. 26.Best estimate of 729 + 354? (a) 1100 (b) 900 (c) 1300
  27. 27.Best estimate of 33 × 16? (a) 600 (b) 6000 (c) 60
  28. 28.Best estimate of 66 × 87? (a) 63000 (b) 6300 (c) 630
  29. 29.Best estimate of 783 + 487? (a) 1500 (b) 1100 (c) 1300
  30. 30.Best estimate of 94 × 98? (a) 900 (b) 9000 (c) 90000
  31. 31.Best estimate of 91 × 89? (a) 810 (b) 81000 (c) 8100
  32. 32.Best estimate of 571 + 557? (a) 1200 (b) 1400 (c) 1000
  33. 33.Best estimate of 32 × 98? (a) 300 (b) 3000 (c) 30000
  34. 34.Best estimate of 203 + 269? (a) 700 (b) 300 (c) 500
  35. 35.Best estimate of 809 + 240? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 26 × 24? (a) 6000 (b) 600 (c) 60
  37. 37.Best estimate of 53 × 44? (a) 200 (b) 2000 (c) 20000
  38. 38.Best estimate of 589 + 398? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 50 × 44? (a) 2000 (b) 20000 (c) 200
  40. 40.Best estimate of 489 + 124? (a) 400 (b) 800 (c) 600

Answer key

  1. 2700
  2. 4200
  3. 2400
  4. 3600
  5. 1100
  6. 500
  7. 2400
  8. 900
  9. 500
  10. 1200
  11. 1000
  12. 1200
  13. 1600
  14. 4800
  15. 1500
  16. 1800
  17. 600
  18. 1400
  19. 2800
  20. 900
  21. 1000
  22. 1000
  23. 1000
  24. 400
  25. 1400
  26. 1100
  27. 600
  28. 6300
  29. 1300
  30. 9000
  31. 8100
  32. 1200
  33. 3000
  34. 500
  35. 1000
  36. 600
  37. 2000
  38. 1000
  39. 2000
  40. 600

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