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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 778 · 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 449 + 646? (a) 800 (b) 1000 (c) 1200
  2. 2.Best estimate of 601 + 364? (a) 1000 (b) 1200 (c) 800
  3. 3.Best estimate of 667 + 207? (a) 900 (b) 700 (c) 1100
  4. 4.Best estimate of 264 + 695? (a) 1200 (b) 1000 (c) 800
  5. 5.Best estimate of 94 × 30? (a) 2700 (b) 27000 (c) 270
  6. 6.Best estimate of 74 × 96? (a) 70000 (b) 700 (c) 7000
  7. 7.Best estimate of 858 + 600? (a) 1700 (b) 1300 (c) 1500
  8. 8.Best estimate of 198 + 221? (a) 400 (b) 600 (c) 200
  9. 9.Best estimate of 49 × 23? (a) 100 (b) 10000 (c) 1000
  10. 10.Best estimate of 292 + 735? (a) 1000 (b) 1200 (c) 800
  11. 11.Best estimate of 16 × 68? (a) 14000 (b) 140 (c) 1400
  12. 12.Best estimate of 199 + 192? (a) 600 (b) 200 (c) 400
  13. 13.Best estimate of 68 × 30? (a) 2100 (b) 21000 (c) 210
  14. 14.Best estimate of 653 + 273? (a) 800 (b) 1000 (c) 1200
  15. 15.Best estimate of 84 × 22? (a) 1600 (b) 16000 (c) 160
  16. 16.Best estimate of 30 × 90? (a) 27000 (b) 270 (c) 2700
  17. 17.Best estimate of 47 × 36? (a) 20000 (b) 200 (c) 2000
  18. 18.Best estimate of 16 × 43? (a) 8000 (b) 80 (c) 800
  19. 19.Best estimate of 706 + 568? (a) 1500 (b) 1100 (c) 1300
  20. 20.Best estimate of 479 + 855? (a) 1200 (b) 1400 (c) 1600
  21. 21.Best estimate of 683 + 498? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 785 + 130? (a) 700 (b) 1100 (c) 900
  23. 23.Best estimate of 274 + 747? (a) 1000 (b) 1200 (c) 800
  24. 24.Best estimate of 761 + 244? (a) 1200 (b) 800 (c) 1000
  25. 25.Best estimate of 12 × 28? (a) 30 (b) 300 (c) 3000
  26. 26.Best estimate of 92 × 77? (a) 72000 (b) 720 (c) 7200
  27. 27.Best estimate of 12 × 31? (a) 300 (b) 3000 (c) 30
  28. 28.Best estimate of 723 + 877? (a) 1800 (b) 1400 (c) 1600
  29. 29.Best estimate of 259 + 156? (a) 500 (b) 300 (c) 700
  30. 30.Best estimate of 749 + 363? (a) 1100 (b) 900 (c) 1300
  31. 31.Best estimate of 87 × 93? (a) 81000 (b) 810 (c) 8100
  32. 32.Best estimate of 618 + 859? (a) 1300 (b) 1700 (c) 1500
  33. 33.Best estimate of 421 + 495? (a) 700 (b) 900 (c) 1100
  34. 34.Best estimate of 242 + 438? (a) 400 (b) 800 (c) 600
  35. 35.Best estimate of 443 + 852? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 122 + 152? (a) 100 (b) 300 (c) 500
  37. 37.Best estimate of 558 + 844? (a) 1200 (b) 1600 (c) 1400
  38. 38.Best estimate of 649 + 727? (a) 1300 (b) 1500 (c) 1100
  39. 39.Best estimate of 54 × 17? (a) 1000 (b) 100 (c) 10000
  40. 40.Best estimate of 51 × 48? (a) 25000 (b) 250 (c) 2500

Answer key

  1. 1000
  2. 1000
  3. 900
  4. 1000
  5. 2700
  6. 7000
  7. 1500
  8. 400
  9. 1000
  10. 1000
  11. 1400
  12. 400
  13. 2100
  14. 1000
  15. 1600
  16. 2700
  17. 2000
  18. 800
  19. 1300
  20. 1400
  21. 1200
  22. 900
  23. 1000
  24. 1000
  25. 300
  26. 7200
  27. 300
  28. 1600
  29. 500
  30. 1100
  31. 8100
  32. 1500
  33. 900
  34. 600
  35. 1300
  36. 300
  37. 1400
  38. 1300
  39. 1000
  40. 2500

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