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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 669 · 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 152 + 408? (a) 600 (b) 400 (c) 800
  2. 2.Best estimate of 861 + 534? (a) 1400 (b) 1600 (c) 1200
  3. 3.Best estimate of 13 × 90? (a) 900 (b) 9000 (c) 90
  4. 4.Best estimate of 209 + 148? (a) 500 (b) 300 (c) 100
  5. 5.Best estimate of 90 × 83? (a) 72000 (b) 7200 (c) 720
  6. 6.Best estimate of 824 + 200? (a) 800 (b) 1200 (c) 1000
  7. 7.Best estimate of 755 + 535? (a) 1500 (b) 1300 (c) 1100
  8. 8.Best estimate of 821 + 396? (a) 1400 (b) 1000 (c) 1200
  9. 9.Best estimate of 60 × 21? (a) 1200 (b) 12000 (c) 120
  10. 10.Best estimate of 23 × 18? (a) 4000 (b) 40 (c) 400
  11. 11.Best estimate of 66 × 23? (a) 1400 (b) 140 (c) 14000
  12. 12.Best estimate of 90 × 77? (a) 7200 (b) 720 (c) 72000
  13. 13.Best estimate of 474 + 214? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 354 + 238? (a) 800 (b) 600 (c) 400
  15. 15.Best estimate of 56 × 28? (a) 18000 (b) 180 (c) 1800
  16. 16.Best estimate of 492 + 670? (a) 1200 (b) 1400 (c) 1000
  17. 17.Best estimate of 866 + 770? (a) 1900 (b) 1700 (c) 1500
  18. 18.Best estimate of 813 + 744? (a) 1700 (b) 1300 (c) 1500
  19. 19.Best estimate of 16 × 86? (a) 180 (b) 1800 (c) 18000
  20. 20.Best estimate of 178 + 581? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 180 + 695? (a) 1100 (b) 900 (c) 700
  22. 22.Best estimate of 34 × 72? (a) 2100 (b) 210 (c) 21000
  23. 23.Best estimate of 60 × 63? (a) 360 (b) 3600 (c) 36000
  24. 24.Best estimate of 23 × 86? (a) 18000 (b) 1800 (c) 180
  25. 25.Best estimate of 79 × 26? (a) 24000 (b) 2400 (c) 240
  26. 26.Best estimate of 273 + 317? (a) 400 (b) 800 (c) 600
  27. 27.Best estimate of 93 × 17? (a) 1800 (b) 18000 (c) 180
  28. 28.Best estimate of 47 × 33? (a) 1500 (b) 150 (c) 15000
  29. 29.Best estimate of 143 + 662? (a) 800 (b) 600 (c) 1000
  30. 30.Best estimate of 31 × 69? (a) 21000 (b) 2100 (c) 210
  31. 31.Best estimate of 33 × 76? (a) 24000 (b) 240 (c) 2400
  32. 32.Best estimate of 49 × 32? (a) 150 (b) 15000 (c) 1500
  33. 33.Best estimate of 51 × 19? (a) 10000 (b) 100 (c) 1000
  34. 34.Best estimate of 32 × 16? (a) 600 (b) 6000 (c) 60
  35. 35.Best estimate of 792 + 291? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 68 × 34? (a) 210 (b) 21000 (c) 2100
  37. 37.Best estimate of 37 × 26? (a) 1200 (b) 12000 (c) 120
  38. 38.Best estimate of 409 + 155? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 540 + 856? (a) 1200 (b) 1600 (c) 1400
  40. 40.Best estimate of 56 × 46? (a) 300 (b) 3000 (c) 30000

Answer key

  1. 600
  2. 1400
  3. 900
  4. 300
  5. 7200
  6. 1000
  7. 1300
  8. 1200
  9. 1200
  10. 400
  11. 1400
  12. 7200
  13. 700
  14. 600
  15. 1800
  16. 1200
  17. 1700
  18. 1500
  19. 1800
  20. 800
  21. 900
  22. 2100
  23. 3600
  24. 1800
  25. 2400
  26. 600
  27. 1800
  28. 1500
  29. 800
  30. 2100
  31. 2400
  32. 1500
  33. 1000
  34. 600
  35. 1100
  36. 2100
  37. 1200
  38. 600
  39. 1400
  40. 3000

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