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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 580 · 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 36 × 84? (a) 320 (b) 32000 (c) 3200
  2. 2.Best estimate of 96 × 71? (a) 700 (b) 7000 (c) 70000
  3. 3.Best estimate of 59 × 86? (a) 54000 (b) 5400 (c) 540
  4. 4.Best estimate of 173 + 306? (a) 700 (b) 500 (c) 300
  5. 5.Best estimate of 878 + 805? (a) 1700 (b) 1500 (c) 1900
  6. 6.Best estimate of 464 + 377? (a) 1100 (b) 700 (c) 900
  7. 7.Best estimate of 68 × 38? (a) 2800 (b) 28000 (c) 280
  8. 8.Best estimate of 814 + 475? (a) 1100 (b) 1300 (c) 1500
  9. 9.Best estimate of 869 + 642? (a) 1500 (b) 1300 (c) 1700
  10. 10.Best estimate of 323 + 377? (a) 500 (b) 900 (c) 700
  11. 11.Best estimate of 50 × 32? (a) 15000 (b) 150 (c) 1500
  12. 12.Best estimate of 36 × 98? (a) 400 (b) 4000 (c) 40000
  13. 13.Best estimate of 758 + 377? (a) 1200 (b) 1400 (c) 1000
  14. 14.Best estimate of 18 × 49? (a) 1000 (b) 100 (c) 10000
  15. 15.Best estimate of 245 + 863? (a) 1300 (b) 1100 (c) 900
  16. 16.Best estimate of 154 + 591? (a) 1000 (b) 800 (c) 600
  17. 17.Best estimate of 30 × 81? (a) 2400 (b) 24000 (c) 240
  18. 18.Best estimate of 26 × 66? (a) 210 (b) 21000 (c) 2100
  19. 19.Best estimate of 60 × 48? (a) 3000 (b) 30000 (c) 300
  20. 20.Best estimate of 122 + 278? (a) 600 (b) 200 (c) 400
  21. 21.Best estimate of 16 × 79? (a) 1600 (b) 160 (c) 16000
  22. 22.Best estimate of 405 + 454? (a) 900 (b) 700 (c) 1100
  23. 23.Best estimate of 874 + 256? (a) 1200 (b) 1000 (c) 1400
  24. 24.Best estimate of 34 × 13? (a) 300 (b) 30 (c) 3000
  25. 25.Best estimate of 92 × 46? (a) 45000 (b) 450 (c) 4500
  26. 26.Best estimate of 330 + 810? (a) 1300 (b) 1100 (c) 900
  27. 27.Best estimate of 76 × 98? (a) 80000 (b) 800 (c) 8000
  28. 28.Best estimate of 54 × 61? (a) 300 (b) 30000 (c) 3000
  29. 29.Best estimate of 39 × 54? (a) 2000 (b) 200 (c) 20000
  30. 30.Best estimate of 91 × 60? (a) 54000 (b) 5400 (c) 540
  31. 31.Best estimate of 98 × 54? (a) 500 (b) 5000 (c) 50000
  32. 32.Best estimate of 94 × 14? (a) 90 (b) 9000 (c) 900
  33. 33.Best estimate of 120 + 353? (a) 700 (b) 300 (c) 500
  34. 34.Best estimate of 140 + 371? (a) 500 (b) 700 (c) 300
  35. 35.Best estimate of 170 + 507? (a) 500 (b) 700 (c) 900
  36. 36.Best estimate of 230 + 246? (a) 600 (b) 400 (c) 200
  37. 37.Best estimate of 847 + 657? (a) 1500 (b) 1700 (c) 1300
  38. 38.Best estimate of 26 × 14? (a) 300 (b) 30 (c) 3000
  39. 39.Best estimate of 448 + 707? (a) 900 (b) 1100 (c) 1300
  40. 40.Best estimate of 54 × 66? (a) 3500 (b) 35000 (c) 350

Answer key

  1. 3200
  2. 7000
  3. 5400
  4. 500
  5. 1700
  6. 900
  7. 2800
  8. 1300
  9. 1500
  10. 700
  11. 1500
  12. 4000
  13. 1200
  14. 1000
  15. 1100
  16. 800
  17. 2400
  18. 2100
  19. 3000
  20. 400
  21. 1600
  22. 900
  23. 1200
  24. 300
  25. 4500
  26. 1100
  27. 8000
  28. 3000
  29. 2000
  30. 5400
  31. 5000
  32. 900
  33. 500
  34. 500
  35. 700
  36. 400
  37. 1500
  38. 300
  39. 1100
  40. 3500

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