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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 317 · 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 12 × 89? (a) 90 (b) 900 (c) 9000
  2. 2.Best estimate of 61 × 34? (a) 18000 (b) 1800 (c) 180
  3. 3.Best estimate of 214 + 288? (a) 500 (b) 700 (c) 300
  4. 4.Best estimate of 653 + 446? (a) 1300 (b) 1100 (c) 900
  5. 5.Best estimate of 64 × 41? (a) 24000 (b) 2400 (c) 240
  6. 6.Best estimate of 300 + 751? (a) 1300 (b) 900 (c) 1100
  7. 7.Best estimate of 98 × 39? (a) 40000 (b) 400 (c) 4000
  8. 8.Best estimate of 72 × 77? (a) 56000 (b) 560 (c) 5600
  9. 9.Best estimate of 796 + 373? (a) 1000 (b) 1400 (c) 1200
  10. 10.Best estimate of 605 + 745? (a) 1100 (b) 1500 (c) 1300
  11. 11.Best estimate of 44 × 92? (a) 3600 (b) 36000 (c) 360
  12. 12.Best estimate of 523 + 705? (a) 1200 (b) 1400 (c) 1000
  13. 13.Best estimate of 16 × 52? (a) 1000 (b) 100 (c) 10000
  14. 14.Best estimate of 791 + 241? (a) 1000 (b) 1200 (c) 800
  15. 15.Best estimate of 211 + 568? (a) 600 (b) 1000 (c) 800
  16. 16.Best estimate of 729 + 289? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 380 + 353? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 69 × 33? (a) 210 (b) 2100 (c) 21000
  19. 19.Best estimate of 72 × 73? (a) 49000 (b) 4900 (c) 490
  20. 20.Best estimate of 77 × 83? (a) 6400 (b) 64000 (c) 640
  21. 21.Best estimate of 698 + 608? (a) 1300 (b) 1500 (c) 1100
  22. 22.Best estimate of 16 × 70? (a) 140 (b) 14000 (c) 1400
  23. 23.Best estimate of 149 + 463? (a) 400 (b) 800 (c) 600
  24. 24.Best estimate of 821 + 818? (a) 1800 (b) 1600 (c) 1400
  25. 25.Best estimate of 834 + 184? (a) 800 (b) 1200 (c) 1000
  26. 26.Best estimate of 36 × 29? (a) 12000 (b) 1200 (c) 120
  27. 27.Best estimate of 735 + 651? (a) 1400 (b) 1200 (c) 1600
  28. 28.Best estimate of 816 + 327? (a) 1100 (b) 1300 (c) 900
  29. 29.Best estimate of 876 + 172? (a) 1100 (b) 900 (c) 1300
  30. 30.Best estimate of 544 + 159? (a) 500 (b) 700 (c) 900
  31. 31.Best estimate of 652 + 852? (a) 1800 (b) 1400 (c) 1600
  32. 32.Best estimate of 82 × 26? (a) 2400 (b) 240 (c) 24000
  33. 33.Best estimate of 59 × 79? (a) 4800 (b) 48000 (c) 480
  34. 34.Best estimate of 49 × 96? (a) 50000 (b) 500 (c) 5000
  35. 35.Best estimate of 42 × 16? (a) 8000 (b) 800 (c) 80
  36. 36.Best estimate of 711 + 698? (a) 1200 (b) 1400 (c) 1600
  37. 37.Best estimate of 73 × 46? (a) 350 (b) 35000 (c) 3500
  38. 38.Best estimate of 71 × 82? (a) 56000 (b) 5600 (c) 560
  39. 39.Best estimate of 36 × 81? (a) 320 (b) 32000 (c) 3200
  40. 40.Best estimate of 320 + 426? (a) 700 (b) 500 (c) 900

Answer key

  1. 900
  2. 1800
  3. 500
  4. 1100
  5. 2400
  6. 1100
  7. 4000
  8. 5600
  9. 1200
  10. 1300
  11. 3600
  12. 1200
  13. 1000
  14. 1000
  15. 800
  16. 1000
  17. 800
  18. 2100
  19. 4900
  20. 6400
  21. 1300
  22. 1400
  23. 600
  24. 1600
  25. 1000
  26. 1200
  27. 1400
  28. 1100
  29. 1100
  30. 700
  31. 1600
  32. 2400
  33. 4800
  34. 5000
  35. 800
  36. 1400
  37. 3500
  38. 5600
  39. 3200
  40. 700

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