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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 551 · 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 49 × 81? (a) 4000 (b) 40000 (c) 400
  2. 2.Best estimate of 53 × 57? (a) 3000 (b) 30000 (c) 300
  3. 3.Best estimate of 26 × 91? (a) 2700 (b) 270 (c) 27000
  4. 4.Best estimate of 36 × 21? (a) 8000 (b) 800 (c) 80
  5. 5.Best estimate of 80 × 56? (a) 4800 (b) 48000 (c) 480
  6. 6.Best estimate of 675 + 685? (a) 1400 (b) 1600 (c) 1200
  7. 7.Best estimate of 14 × 87? (a) 900 (b) 90 (c) 9000
  8. 8.Best estimate of 608 + 713? (a) 1300 (b) 1500 (c) 1100
  9. 9.Best estimate of 64 × 63? (a) 36000 (b) 3600 (c) 360
  10. 10.Best estimate of 57 × 83? (a) 480 (b) 48000 (c) 4800
  11. 11.Best estimate of 259 + 249? (a) 500 (b) 700 (c) 300
  12. 12.Best estimate of 37 × 17? (a) 80 (b) 8000 (c) 800
  13. 13.Best estimate of 26 × 37? (a) 1200 (b) 120 (c) 12000
  14. 14.Best estimate of 138 + 780? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 146 + 584? (a) 700 (b) 500 (c) 900
  16. 16.Best estimate of 82 × 63? (a) 48000 (b) 4800 (c) 480
  17. 17.Best estimate of 471 + 877? (a) 1200 (b) 1400 (c) 1600
  18. 18.Best estimate of 647 + 185? (a) 800 (b) 600 (c) 1000
  19. 19.Best estimate of 16 × 70? (a) 1400 (b) 140 (c) 14000
  20. 20.Best estimate of 871 + 239? (a) 1100 (b) 1300 (c) 900
  21. 21.Best estimate of 653 + 638? (a) 1300 (b) 1100 (c) 1500
  22. 22.Best estimate of 290 + 490? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 209 + 561? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 39 × 53? (a) 2000 (b) 200 (c) 20000
  25. 25.Best estimate of 820 + 668? (a) 1300 (b) 1500 (c) 1700
  26. 26.Best estimate of 37 × 81? (a) 32000 (b) 3200 (c) 320
  27. 27.Best estimate of 27 × 34? (a) 9000 (b) 90 (c) 900
  28. 28.Best estimate of 24 × 40? (a) 80 (b) 800 (c) 8000
  29. 29.Best estimate of 47 × 40? (a) 20000 (b) 200 (c) 2000
  30. 30.Best estimate of 148 + 500? (a) 600 (b) 800 (c) 400
  31. 31.Best estimate of 44 × 21? (a) 800 (b) 8000 (c) 80
  32. 32.Best estimate of 18 × 26? (a) 6000 (b) 60 (c) 600
  33. 33.Best estimate of 63 × 56? (a) 360 (b) 36000 (c) 3600
  34. 34.Best estimate of 467 + 553? (a) 1300 (b) 1100 (c) 900
  35. 35.Best estimate of 79 × 13? (a) 800 (b) 80 (c) 8000
  36. 36.Best estimate of 603 + 175? (a) 1000 (b) 600 (c) 800
  37. 37.Best estimate of 657 + 648? (a) 1300 (b) 1100 (c) 1500
  38. 38.Best estimate of 266 + 709? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 36 × 42? (a) 160 (b) 1600 (c) 16000
  40. 40.Best estimate of 74 × 51? (a) 350 (b) 35000 (c) 3500

Answer key

  1. 4000
  2. 3000
  3. 2700
  4. 800
  5. 4800
  6. 1400
  7. 900
  8. 1300
  9. 3600
  10. 4800
  11. 500
  12. 800
  13. 1200
  14. 900
  15. 700
  16. 4800
  17. 1400
  18. 800
  19. 1400
  20. 1100
  21. 1300
  22. 800
  23. 800
  24. 2000
  25. 1500
  26. 3200
  27. 900
  28. 800
  29. 2000
  30. 600
  31. 800
  32. 600
  33. 3600
  34. 1100
  35. 800
  36. 800
  37. 1300
  38. 1000
  39. 1600
  40. 3500

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