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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 858 · 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 93 × 47? (a) 450 (b) 45000 (c) 4500
  2. 2.Best estimate of 747 + 416? (a) 1100 (b) 900 (c) 1300
  3. 3.Best estimate of 77 × 73? (a) 5600 (b) 56000 (c) 560
  4. 4.Best estimate of 185 + 667? (a) 700 (b) 900 (c) 1100
  5. 5.Best estimate of 24 × 59? (a) 12000 (b) 1200 (c) 120
  6. 6.Best estimate of 52 × 26? (a) 15000 (b) 1500 (c) 150
  7. 7.Best estimate of 551 + 741? (a) 1300 (b) 1500 (c) 1100
  8. 8.Best estimate of 22 × 37? (a) 800 (b) 8000 (c) 80
  9. 9.Best estimate of 600 + 359? (a) 800 (b) 1200 (c) 1000
  10. 10.Best estimate of 135 + 643? (a) 700 (b) 500 (c) 900
  11. 11.Best estimate of 51 × 23? (a) 10000 (b) 1000 (c) 100
  12. 12.Best estimate of 77 × 49? (a) 400 (b) 40000 (c) 4000
  13. 13.Best estimate of 197 + 374? (a) 600 (b) 800 (c) 400
  14. 14.Best estimate of 673 + 576? (a) 1100 (b) 1300 (c) 1500
  15. 15.Best estimate of 729 + 254? (a) 1000 (b) 800 (c) 1200
  16. 16.Best estimate of 26 × 17? (a) 60 (b) 600 (c) 6000
  17. 17.Best estimate of 490 + 360? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 79 × 13? (a) 8000 (b) 80 (c) 800
  19. 19.Best estimate of 255 + 120? (a) 200 (b) 400 (c) 600
  20. 20.Best estimate of 88 × 34? (a) 2700 (b) 27000 (c) 270
  21. 21.Best estimate of 14 × 74? (a) 700 (b) 7000 (c) 70
  22. 22.Best estimate of 69 × 30? (a) 210 (b) 21000 (c) 2100
  23. 23.Best estimate of 50 × 76? (a) 4000 (b) 40000 (c) 400
  24. 24.Best estimate of 605 + 390? (a) 1200 (b) 1000 (c) 800
  25. 25.Best estimate of 720 + 510? (a) 1200 (b) 1000 (c) 1400
  26. 26.Best estimate of 293 + 128? (a) 200 (b) 600 (c) 400
  27. 27.Best estimate of 97 × 22? (a) 200 (b) 2000 (c) 20000
  28. 28.Best estimate of 58 × 79? (a) 4800 (b) 480 (c) 48000
  29. 29.Best estimate of 46 × 76? (a) 4000 (b) 40000 (c) 400
  30. 30.Best estimate of 57 × 51? (a) 30000 (b) 300 (c) 3000
  31. 31.Best estimate of 76 × 13? (a) 800 (b) 80 (c) 8000
  32. 32.Best estimate of 82 × 36? (a) 3200 (b) 32000 (c) 320
  33. 33.Best estimate of 531 + 193? (a) 500 (b) 700 (c) 900
  34. 34.Best estimate of 31 × 56? (a) 18000 (b) 180 (c) 1800
  35. 35.Best estimate of 566 + 137? (a) 900 (b) 500 (c) 700
  36. 36.Best estimate of 347 + 855? (a) 1000 (b) 1200 (c) 1400
  37. 37.Best estimate of 68 × 60? (a) 420 (b) 42000 (c) 4200
  38. 38.Best estimate of 79 × 96? (a) 800 (b) 80000 (c) 8000
  39. 39.Best estimate of 66 × 86? (a) 630 (b) 6300 (c) 63000
  40. 40.Best estimate of 61 × 60? (a) 3600 (b) 36000 (c) 360

Answer key

  1. 4500
  2. 1100
  3. 5600
  4. 900
  5. 1200
  6. 1500
  7. 1300
  8. 800
  9. 1000
  10. 700
  11. 1000
  12. 4000
  13. 600
  14. 1300
  15. 1000
  16. 600
  17. 900
  18. 800
  19. 400
  20. 2700
  21. 700
  22. 2100
  23. 4000
  24. 1000
  25. 1200
  26. 400
  27. 2000
  28. 4800
  29. 4000
  30. 3000
  31. 800
  32. 3200
  33. 700
  34. 1800
  35. 700
  36. 1200
  37. 4200
  38. 8000
  39. 6300
  40. 3600

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