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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 21 · 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 13 × 49? (a) 500 (b) 50 (c) 5000
  2. 2.Best estimate of 879 + 825? (a) 1500 (b) 1900 (c) 1700
  3. 3.Best estimate of 243 + 704? (a) 900 (b) 700 (c) 1100
  4. 4.Best estimate of 70 × 36? (a) 2800 (b) 28000 (c) 280
  5. 5.Best estimate of 90 × 51? (a) 4500 (b) 45000 (c) 450
  6. 6.Best estimate of 41 × 40? (a) 160 (b) 16000 (c) 1600
  7. 7.Best estimate of 58 × 77? (a) 480 (b) 48000 (c) 4800
  8. 8.Best estimate of 759 + 354? (a) 1000 (b) 1200 (c) 1400
  9. 9.Best estimate of 86 × 18? (a) 18000 (b) 1800 (c) 180
  10. 10.Best estimate of 421 + 412? (a) 800 (b) 600 (c) 1000
  11. 11.Best estimate of 564 + 642? (a) 1400 (b) 1000 (c) 1200
  12. 12.Best estimate of 30 × 26? (a) 900 (b) 9000 (c) 90
  13. 13.Best estimate of 22 × 27? (a) 600 (b) 60 (c) 6000
  14. 14.Best estimate of 294 + 757? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 56 × 46? (a) 30000 (b) 3000 (c) 300
  16. 16.Best estimate of 610 + 294? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 73 × 38? (a) 280 (b) 28000 (c) 2800
  18. 18.Best estimate of 451 + 727? (a) 1400 (b) 1000 (c) 1200
  19. 19.Best estimate of 705 + 655? (a) 1400 (b) 1600 (c) 1200
  20. 20.Best estimate of 41 × 94? (a) 3600 (b) 360 (c) 36000
  21. 21.Best estimate of 229 + 725? (a) 900 (b) 1100 (c) 700
  22. 22.Best estimate of 71 × 13? (a) 70 (b) 7000 (c) 700
  23. 23.Best estimate of 32 × 76? (a) 24000 (b) 240 (c) 2400
  24. 24.Best estimate of 97 × 68? (a) 7000 (b) 700 (c) 70000
  25. 25.Best estimate of 328 + 838? (a) 1300 (b) 900 (c) 1100
  26. 26.Best estimate of 230 + 770? (a) 1200 (b) 1000 (c) 800
  27. 27.Best estimate of 415 + 689? (a) 900 (b) 1100 (c) 1300
  28. 28.Best estimate of 199 + 505? (a) 500 (b) 700 (c) 900
  29. 29.Best estimate of 656 + 136? (a) 800 (b) 1000 (c) 600
  30. 30.Best estimate of 619 + 484? (a) 1100 (b) 900 (c) 1300
  31. 31.Best estimate of 392 + 131? (a) 700 (b) 500 (c) 300
  32. 32.Best estimate of 28 × 63? (a) 1800 (b) 18000 (c) 180
  33. 33.Best estimate of 288 + 245? (a) 500 (b) 700 (c) 300
  34. 34.Best estimate of 16 × 56? (a) 12000 (b) 120 (c) 1200
  35. 35.Best estimate of 29 × 13? (a) 30 (b) 300 (c) 3000
  36. 36.Best estimate of 157 + 611? (a) 1000 (b) 600 (c) 800
  37. 37.Best estimate of 20 × 22? (a) 400 (b) 40 (c) 4000
  38. 38.Best estimate of 83 × 17? (a) 16000 (b) 1600 (c) 160
  39. 39.Best estimate of 58 × 84? (a) 480 (b) 4800 (c) 48000
  40. 40.Best estimate of 49 × 92? (a) 450 (b) 4500 (c) 45000

Answer key

  1. 500
  2. 1700
  3. 900
  4. 2800
  5. 4500
  6. 1600
  7. 4800
  8. 1200
  9. 1800
  10. 800
  11. 1200
  12. 900
  13. 600
  14. 1100
  15. 3000
  16. 900
  17. 2800
  18. 1200
  19. 1400
  20. 3600
  21. 900
  22. 700
  23. 2400
  24. 7000
  25. 1100
  26. 1000
  27. 1100
  28. 700
  29. 800
  30. 1100
  31. 500
  32. 1800
  33. 500
  34. 1200
  35. 300
  36. 800
  37. 400
  38. 1600
  39. 4800
  40. 4500

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