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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 173 · 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 × 20? (a) 80 (b) 800 (c) 8000
  2. 2.Best estimate of 223 + 530? (a) 900 (b) 700 (c) 500
  3. 3.Best estimate of 43 × 61? (a) 2400 (b) 24000 (c) 240
  4. 4.Best estimate of 66 × 53? (a) 3500 (b) 350 (c) 35000
  5. 5.Best estimate of 24 × 88? (a) 180 (b) 1800 (c) 18000
  6. 6.Best estimate of 419 + 563? (a) 1000 (b) 800 (c) 1200
  7. 7.Best estimate of 138 + 839? (a) 1100 (b) 700 (c) 900
  8. 8.Best estimate of 32 × 51? (a) 15000 (b) 1500 (c) 150
  9. 9.Best estimate of 658 + 780? (a) 1500 (b) 1300 (c) 1700
  10. 10.Best estimate of 456 + 577? (a) 1300 (b) 1100 (c) 900
  11. 11.Best estimate of 560 + 757? (a) 1400 (b) 1600 (c) 1200
  12. 12.Best estimate of 410 + 749? (a) 1300 (b) 1100 (c) 900
  13. 13.Best estimate of 66 × 97? (a) 7000 (b) 70000 (c) 700
  14. 14.Best estimate of 287 + 121? (a) 400 (b) 600 (c) 200
  15. 15.Best estimate of 213 + 145? (a) 500 (b) 100 (c) 300
  16. 16.Best estimate of 327 + 738? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 791 + 433? (a) 1400 (b) 1000 (c) 1200
  18. 18.Best estimate of 335 + 696? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 52 × 33? (a) 15000 (b) 1500 (c) 150
  20. 20.Best estimate of 73 × 77? (a) 56000 (b) 560 (c) 5600
  21. 21.Best estimate of 23 × 44? (a) 80 (b) 8000 (c) 800
  22. 22.Best estimate of 16 × 16? (a) 400 (b) 40 (c) 4000
  23. 23.Best estimate of 47 × 29? (a) 150 (b) 15000 (c) 1500
  24. 24.Best estimate of 307 + 186? (a) 300 (b) 500 (c) 700
  25. 25.Best estimate of 526 + 623? (a) 900 (b) 1100 (c) 1300
  26. 26.Best estimate of 86 × 42? (a) 360 (b) 3600 (c) 36000
  27. 27.Best estimate of 189 + 794? (a) 1000 (b) 1200 (c) 800
  28. 28.Best estimate of 193 + 753? (a) 1200 (b) 1000 (c) 800
  29. 29.Best estimate of 64 × 72? (a) 420 (b) 4200 (c) 42000
  30. 30.Best estimate of 52 × 39? (a) 20000 (b) 200 (c) 2000
  31. 31.Best estimate of 23 × 51? (a) 10000 (b) 1000 (c) 100
  32. 32.Best estimate of 427 + 729? (a) 1300 (b) 900 (c) 1100
  33. 33.Best estimate of 62 × 42? (a) 2400 (b) 240 (c) 24000
  34. 34.Best estimate of 68 × 56? (a) 42000 (b) 4200 (c) 420
  35. 35.Best estimate of 196 + 859? (a) 900 (b) 1100 (c) 1300
  36. 36.Best estimate of 266 + 246? (a) 300 (b) 700 (c) 500
  37. 37.Best estimate of 47 × 36? (a) 20000 (b) 2000 (c) 200
  38. 38.Best estimate of 34 × 13? (a) 300 (b) 30 (c) 3000
  39. 39.Best estimate of 36 × 24? (a) 80 (b) 800 (c) 8000
  40. 40.Best estimate of 66 × 94? (a) 6300 (b) 63000 (c) 630

Answer key

  1. 800
  2. 700
  3. 2400
  4. 3500
  5. 1800
  6. 1000
  7. 900
  8. 1500
  9. 1500
  10. 1100
  11. 1400
  12. 1100
  13. 7000
  14. 400
  15. 300
  16. 1000
  17. 1200
  18. 1000
  19. 1500
  20. 5600
  21. 800
  22. 400
  23. 1500
  24. 500
  25. 1100
  26. 3600
  27. 1000
  28. 1000
  29. 4200
  30. 2000
  31. 1000
  32. 1100
  33. 2400
  34. 4200
  35. 1100
  36. 500
  37. 2000
  38. 300
  39. 800
  40. 6300

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