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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 205 · 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 51 × 68? (a) 3500 (b) 350 (c) 35000
  2. 2.Best estimate of 66 × 57? (a) 420 (b) 42000 (c) 4200
  3. 3.Best estimate of 78 × 96? (a) 8000 (b) 800 (c) 80000
  4. 4.Best estimate of 184 + 320? (a) 700 (b) 300 (c) 500
  5. 5.Best estimate of 92 × 39? (a) 3600 (b) 360 (c) 36000
  6. 6.Best estimate of 171 + 361? (a) 800 (b) 400 (c) 600
  7. 7.Best estimate of 752 + 283? (a) 900 (b) 1300 (c) 1100
  8. 8.Best estimate of 57 × 34? (a) 180 (b) 18000 (c) 1800
  9. 9.Best estimate of 76 × 22? (a) 16000 (b) 1600 (c) 160
  10. 10.Best estimate of 96 × 76? (a) 80000 (b) 8000 (c) 800
  11. 11.Best estimate of 674 + 705? (a) 1600 (b) 1200 (c) 1400
  12. 12.Best estimate of 433 + 811? (a) 1000 (b) 1200 (c) 1400
  13. 13.Best estimate of 327 + 282? (a) 600 (b) 800 (c) 400
  14. 14.Best estimate of 79 × 54? (a) 400 (b) 40000 (c) 4000
  15. 15.Best estimate of 30 × 66? (a) 21000 (b) 210 (c) 2100
  16. 16.Best estimate of 742 + 277? (a) 1000 (b) 800 (c) 1200
  17. 17.Best estimate of 93 × 57? (a) 5400 (b) 540 (c) 54000
  18. 18.Best estimate of 74 × 12? (a) 7000 (b) 700 (c) 70
  19. 19.Best estimate of 417 + 407? (a) 600 (b) 800 (c) 1000
  20. 20.Best estimate of 168 + 240? (a) 400 (b) 200 (c) 600
  21. 21.Best estimate of 666 + 540? (a) 1200 (b) 1000 (c) 1400
  22. 22.Best estimate of 64 × 67? (a) 42000 (b) 4200 (c) 420
  23. 23.Best estimate of 392 + 633? (a) 1000 (b) 800 (c) 1200
  24. 24.Best estimate of 89 × 59? (a) 54000 (b) 5400 (c) 540
  25. 25.Best estimate of 197 + 398? (a) 600 (b) 400 (c) 800
  26. 26.Best estimate of 36 × 32? (a) 12000 (b) 120 (c) 1200
  27. 27.Best estimate of 67 × 50? (a) 3500 (b) 350 (c) 35000
  28. 28.Best estimate of 22 × 29? (a) 600 (b) 60 (c) 6000
  29. 29.Best estimate of 245 + 226? (a) 400 (b) 200 (c) 600
  30. 30.Best estimate of 651 + 515? (a) 1200 (b) 1000 (c) 1400
  31. 31.Best estimate of 380 + 376? (a) 600 (b) 1000 (c) 800
  32. 32.Best estimate of 16 × 74? (a) 140 (b) 1400 (c) 14000
  33. 33.Best estimate of 73 × 16? (a) 140 (b) 1400 (c) 14000
  34. 34.Best estimate of 80 × 79? (a) 6400 (b) 640 (c) 64000
  35. 35.Best estimate of 76 × 58? (a) 4800 (b) 48000 (c) 480
  36. 36.Best estimate of 481 + 309? (a) 600 (b) 800 (c) 1000
  37. 37.Best estimate of 461 + 520? (a) 800 (b) 1000 (c) 1200
  38. 38.Best estimate of 513 + 163? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 554 + 134? (a) 700 (b) 900 (c) 500
  40. 40.Best estimate of 30 × 56? (a) 18000 (b) 1800 (c) 180

Answer key

  1. 3500
  2. 4200
  3. 8000
  4. 500
  5. 3600
  6. 600
  7. 1100
  8. 1800
  9. 1600
  10. 8000
  11. 1400
  12. 1200
  13. 600
  14. 4000
  15. 2100
  16. 1000
  17. 5400
  18. 700
  19. 800
  20. 400
  21. 1200
  22. 4200
  23. 1000
  24. 5400
  25. 600
  26. 1200
  27. 3500
  28. 600
  29. 400
  30. 1200
  31. 800
  32. 1400
  33. 1400
  34. 6400
  35. 4800
  36. 800
  37. 1000
  38. 700
  39. 700
  40. 1800

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