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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 543 · 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 81 × 17? (a) 1600 (b) 16000 (c) 160
  2. 2.Best estimate of 61 × 63? (a) 36000 (b) 360 (c) 3600
  3. 3.Best estimate of 47 × 88? (a) 4500 (b) 450 (c) 45000
  4. 4.Best estimate of 46 × 31? (a) 150 (b) 15000 (c) 1500
  5. 5.Best estimate of 90 × 21? (a) 18000 (b) 1800 (c) 180
  6. 6.Best estimate of 809 + 353? (a) 1000 (b) 1200 (c) 1400
  7. 7.Best estimate of 273 + 356? (a) 700 (b) 500 (c) 900
  8. 8.Best estimate of 40 × 33? (a) 1200 (b) 120 (c) 12000
  9. 9.Best estimate of 52 × 98? (a) 5000 (b) 50000 (c) 500
  10. 10.Best estimate of 38 × 36? (a) 1600 (b) 160 (c) 16000
  11. 11.Best estimate of 727 + 735? (a) 1600 (b) 1200 (c) 1400
  12. 12.Best estimate of 13 × 62? (a) 60 (b) 600 (c) 6000
  13. 13.Best estimate of 33 × 16? (a) 60 (b) 6000 (c) 600
  14. 14.Best estimate of 98 × 78? (a) 80000 (b) 8000 (c) 800
  15. 15.Best estimate of 127 + 448? (a) 300 (b) 700 (c) 500
  16. 16.Best estimate of 651 + 349? (a) 800 (b) 1200 (c) 1000
  17. 17.Best estimate of 835 + 451? (a) 1500 (b) 1300 (c) 1100
  18. 18.Best estimate of 856 + 527? (a) 1400 (b) 1600 (c) 1200
  19. 19.Best estimate of 276 + 764? (a) 900 (b) 1300 (c) 1100
  20. 20.Best estimate of 28 × 53? (a) 1500 (b) 15000 (c) 150
  21. 21.Best estimate of 16 × 84? (a) 16000 (b) 1600 (c) 160
  22. 22.Best estimate of 271 + 160? (a) 300 (b) 700 (c) 500
  23. 23.Best estimate of 53 × 18? (a) 10000 (b) 1000 (c) 100
  24. 24.Best estimate of 97 × 43? (a) 400 (b) 40000 (c) 4000
  25. 25.Best estimate of 463 + 737? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 61 × 17? (a) 120 (b) 12000 (c) 1200
  27. 27.Best estimate of 13 × 90? (a) 9000 (b) 90 (c) 900
  28. 28.Best estimate of 32 × 66? (a) 21000 (b) 2100 (c) 210
  29. 29.Best estimate of 342 + 293? (a) 600 (b) 800 (c) 400
  30. 30.Best estimate of 27 × 26? (a) 9000 (b) 90 (c) 900
  31. 31.Best estimate of 30 × 14? (a) 300 (b) 3000 (c) 30
  32. 32.Best estimate of 26 × 90? (a) 27000 (b) 2700 (c) 270
  33. 33.Best estimate of 710 + 608? (a) 1100 (b) 1500 (c) 1300
  34. 34.Best estimate of 43 × 22? (a) 8000 (b) 80 (c) 800
  35. 35.Best estimate of 872 + 133? (a) 800 (b) 1200 (c) 1000
  36. 36.Best estimate of 43 × 89? (a) 3600 (b) 36000 (c) 360
  37. 37.Best estimate of 89 × 78? (a) 720 (b) 72000 (c) 7200
  38. 38.Best estimate of 67 × 22? (a) 14000 (b) 140 (c) 1400
  39. 39.Best estimate of 347 + 295? (a) 800 (b) 400 (c) 600
  40. 40.Best estimate of 661 + 179? (a) 1100 (b) 700 (c) 900

Answer key

  1. 1600
  2. 3600
  3. 4500
  4. 1500
  5. 1800
  6. 1200
  7. 700
  8. 1200
  9. 5000
  10. 1600
  11. 1400
  12. 600
  13. 600
  14. 8000
  15. 500
  16. 1000
  17. 1300
  18. 1400
  19. 1100
  20. 1500
  21. 1600
  22. 500
  23. 1000
  24. 4000
  25. 1200
  26. 1200
  27. 900
  28. 2100
  29. 600
  30. 900
  31. 300
  32. 2700
  33. 1300
  34. 800
  35. 1000
  36. 3600
  37. 7200
  38. 1400
  39. 600
  40. 900

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