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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 891 · 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 48 × 12? (a) 50 (b) 500 (c) 5000
  2. 2.Best estimate of 29 × 77? (a) 24000 (b) 240 (c) 2400
  3. 3.Best estimate of 26 × 13? (a) 3000 (b) 30 (c) 300
  4. 4.Best estimate of 458 + 249? (a) 500 (b) 700 (c) 900
  5. 5.Best estimate of 79 × 56? (a) 4800 (b) 48000 (c) 480
  6. 6.Best estimate of 73 × 91? (a) 6300 (b) 63000 (c) 630
  7. 7.Best estimate of 33 × 77? (a) 24000 (b) 2400 (c) 240
  8. 8.Best estimate of 31 × 22? (a) 6000 (b) 600 (c) 60
  9. 9.Best estimate of 453 + 652? (a) 1200 (b) 1400 (c) 1000
  10. 10.Best estimate of 464 + 206? (a) 500 (b) 700 (c) 900
  11. 11.Best estimate of 607 + 437? (a) 1200 (b) 800 (c) 1000
  12. 12.Best estimate of 86 × 38? (a) 3600 (b) 36000 (c) 360
  13. 13.Best estimate of 551 + 745? (a) 1300 (b) 1500 (c) 1100
  14. 14.Best estimate of 552 + 649? (a) 1200 (b) 1000 (c) 1400
  15. 15.Best estimate of 308 + 284? (a) 800 (b) 600 (c) 400
  16. 16.Best estimate of 659 + 142? (a) 1000 (b) 800 (c) 600
  17. 17.Best estimate of 56 × 61? (a) 36000 (b) 360 (c) 3600
  18. 18.Best estimate of 592 + 280? (a) 900 (b) 700 (c) 1100
  19. 19.Best estimate of 80 × 23? (a) 16000 (b) 1600 (c) 160
  20. 20.Best estimate of 333 + 248? (a) 300 (b) 500 (c) 700
  21. 21.Best estimate of 59 × 24? (a) 1200 (b) 12000 (c) 120
  22. 22.Best estimate of 40 × 42? (a) 16000 (b) 160 (c) 1600
  23. 23.Best estimate of 48 × 23? (a) 1000 (b) 10000 (c) 100
  24. 24.Best estimate of 504 + 592? (a) 900 (b) 1100 (c) 1300
  25. 25.Best estimate of 626 + 344? (a) 700 (b) 1100 (c) 900
  26. 26.Best estimate of 842 + 654? (a) 1300 (b) 1500 (c) 1700
  27. 27.Best estimate of 31 × 29? (a) 900 (b) 9000 (c) 90
  28. 28.Best estimate of 34 × 14? (a) 3000 (b) 30 (c) 300
  29. 29.Best estimate of 836 + 404? (a) 1400 (b) 1000 (c) 1200
  30. 30.Best estimate of 726 + 163? (a) 1100 (b) 900 (c) 700
  31. 31.Best estimate of 782 + 628? (a) 1200 (b) 1600 (c) 1400
  32. 32.Best estimate of 770 + 582? (a) 1600 (b) 1400 (c) 1200
  33. 33.Best estimate of 32 × 32? (a) 900 (b) 90 (c) 9000
  34. 34.Best estimate of 77 × 76? (a) 64000 (b) 640 (c) 6400
  35. 35.Best estimate of 30 × 33? (a) 9000 (b) 900 (c) 90
  36. 36.Best estimate of 829 + 782? (a) 1400 (b) 1600 (c) 1800
  37. 37.Best estimate of 224 + 185? (a) 200 (b) 400 (c) 600
  38. 38.Best estimate of 628 + 430? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 473 + 122? (a) 600 (b) 800 (c) 400
  40. 40.Best estimate of 54 × 22? (a) 10000 (b) 100 (c) 1000

Answer key

  1. 500
  2. 2400
  3. 300
  4. 700
  5. 4800
  6. 6300
  7. 2400
  8. 600
  9. 1200
  10. 700
  11. 1000
  12. 3600
  13. 1300
  14. 1200
  15. 600
  16. 800
  17. 3600
  18. 900
  19. 1600
  20. 500
  21. 1200
  22. 1600
  23. 1000
  24. 1100
  25. 900
  26. 1500
  27. 900
  28. 300
  29. 1200
  30. 900
  31. 1400
  32. 1400
  33. 900
  34. 6400
  35. 900
  36. 1600
  37. 400
  38. 1000
  39. 600
  40. 1000

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