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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 820 · 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 58 × 54? (a) 3000 (b) 30000 (c) 300
  2. 2.Best estimate of 21 × 46? (a) 100 (b) 1000 (c) 10000
  3. 3.Best estimate of 46 × 88? (a) 4500 (b) 45000 (c) 450
  4. 4.Best estimate of 336 + 276? (a) 600 (b) 800 (c) 400
  5. 5.Best estimate of 402 + 873? (a) 1300 (b) 1500 (c) 1100
  6. 6.Best estimate of 36 × 41? (a) 16000 (b) 160 (c) 1600
  7. 7.Best estimate of 613 + 560? (a) 1200 (b) 1000 (c) 1400
  8. 8.Best estimate of 302 + 129? (a) 600 (b) 400 (c) 200
  9. 9.Best estimate of 68 × 80? (a) 56000 (b) 5600 (c) 560
  10. 10.Best estimate of 443 + 690? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 749 + 193? (a) 1100 (b) 900 (c) 700
  12. 12.Best estimate of 334 + 209? (a) 500 (b) 700 (c) 300
  13. 13.Best estimate of 26 × 68? (a) 2100 (b) 210 (c) 21000
  14. 14.Best estimate of 309 + 381? (a) 700 (b) 900 (c) 500
  15. 15.Best estimate of 53 × 13? (a) 500 (b) 5000 (c) 50
  16. 16.Best estimate of 157 + 367? (a) 400 (b) 600 (c) 800
  17. 17.Best estimate of 709 + 361? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 19 × 50? (a) 100 (b) 10000 (c) 1000
  19. 19.Best estimate of 98 × 17? (a) 2000 (b) 200 (c) 20000
  20. 20.Best estimate of 30 × 86? (a) 27000 (b) 270 (c) 2700
  21. 21.Best estimate of 73 × 14? (a) 70 (b) 700 (c) 7000
  22. 22.Best estimate of 737 + 575? (a) 1500 (b) 1300 (c) 1100
  23. 23.Best estimate of 491 + 196? (a) 900 (b) 500 (c) 700
  24. 24.Best estimate of 23 × 26? (a) 600 (b) 6000 (c) 60
  25. 25.Best estimate of 24 × 22? (a) 4000 (b) 40 (c) 400
  26. 26.Best estimate of 465 + 174? (a) 700 (b) 500 (c) 900
  27. 27.Best estimate of 764 + 536? (a) 1100 (b) 1300 (c) 1500
  28. 28.Best estimate of 259 + 321? (a) 400 (b) 800 (c) 600
  29. 29.Best estimate of 17 × 36? (a) 80 (b) 8000 (c) 800
  30. 30.Best estimate of 88 × 12? (a) 9000 (b) 900 (c) 90
  31. 31.Best estimate of 19 × 83? (a) 16000 (b) 160 (c) 1600
  32. 32.Best estimate of 692 + 316? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 402 + 811? (a) 1200 (b) 1000 (c) 1400
  34. 34.Best estimate of 177 + 428? (a) 600 (b) 800 (c) 400
  35. 35.Best estimate of 837 + 494? (a) 1500 (b) 1300 (c) 1100
  36. 36.Best estimate of 702 + 522? (a) 1400 (b) 1000 (c) 1200
  37. 37.Best estimate of 89 × 31? (a) 27000 (b) 2700 (c) 270
  38. 38.Best estimate of 60 × 50? (a) 30000 (b) 300 (c) 3000
  39. 39.Best estimate of 126 + 771? (a) 900 (b) 1100 (c) 700
  40. 40.Best estimate of 92 × 50? (a) 450 (b) 45000 (c) 4500

Answer key

  1. 3000
  2. 1000
  3. 4500
  4. 600
  5. 1300
  6. 1600
  7. 1200
  8. 400
  9. 5600
  10. 1100
  11. 900
  12. 500
  13. 2100
  14. 700
  15. 500
  16. 600
  17. 1100
  18. 1000
  19. 2000
  20. 2700
  21. 700
  22. 1300
  23. 700
  24. 600
  25. 400
  26. 700
  27. 1300
  28. 600
  29. 800
  30. 900
  31. 1600
  32. 1000
  33. 1200
  34. 600
  35. 1300
  36. 1200
  37. 2700
  38. 3000
  39. 900
  40. 4500

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