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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 250 · 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 251 + 446? (a) 900 (b) 700 (c) 500
  2. 2.Best estimate of 36 × 51? (a) 2000 (b) 20000 (c) 200
  3. 3.Best estimate of 70 × 80? (a) 5600 (b) 56000 (c) 560
  4. 4.Best estimate of 652 + 456? (a) 1200 (b) 1400 (c) 1000
  5. 5.Best estimate of 49 × 90? (a) 45000 (b) 450 (c) 4500
  6. 6.Best estimate of 191 + 608? (a) 800 (b) 1000 (c) 600
  7. 7.Best estimate of 28 × 61? (a) 180 (b) 1800 (c) 18000
  8. 8.Best estimate of 87 × 68? (a) 63000 (b) 630 (c) 6300
  9. 9.Best estimate of 83 × 94? (a) 72000 (b) 7200 (c) 720
  10. 10.Best estimate of 526 + 324? (a) 800 (b) 1000 (c) 600
  11. 11.Best estimate of 319 + 708? (a) 1000 (b) 1200 (c) 800
  12. 12.Best estimate of 40 × 69? (a) 28000 (b) 280 (c) 2800
  13. 13.Best estimate of 46 × 86? (a) 45000 (b) 450 (c) 4500
  14. 14.Best estimate of 234 + 555? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 73 × 58? (a) 4200 (b) 420 (c) 42000
  16. 16.Best estimate of 84 × 78? (a) 64000 (b) 6400 (c) 640
  17. 17.Best estimate of 94 × 28? (a) 27000 (b) 270 (c) 2700
  18. 18.Best estimate of 606 + 177? (a) 600 (b) 1000 (c) 800
  19. 19.Best estimate of 19 × 26? (a) 6000 (b) 60 (c) 600
  20. 20.Best estimate of 52 × 48? (a) 2500 (b) 25000 (c) 250
  21. 21.Best estimate of 48 × 78? (a) 40000 (b) 4000 (c) 400
  22. 22.Best estimate of 192 + 583? (a) 600 (b) 800 (c) 1000
  23. 23.Best estimate of 36 × 59? (a) 2400 (b) 240 (c) 24000
  24. 24.Best estimate of 24 × 36? (a) 800 (b) 8000 (c) 80
  25. 25.Best estimate of 80 × 87? (a) 72000 (b) 7200 (c) 720
  26. 26.Best estimate of 190 + 755? (a) 1000 (b) 1200 (c) 800
  27. 27.Best estimate of 813 + 134? (a) 1100 (b) 900 (c) 700
  28. 28.Best estimate of 41 × 88? (a) 3600 (b) 36000 (c) 360
  29. 29.Best estimate of 737 + 455? (a) 1400 (b) 1000 (c) 1200
  30. 30.Best estimate of 191 + 375? (a) 600 (b) 800 (c) 400
  31. 31.Best estimate of 365 + 725? (a) 1100 (b) 900 (c) 1300
  32. 32.Best estimate of 90 × 98? (a) 900 (b) 9000 (c) 90000
  33. 33.Best estimate of 78 × 62? (a) 480 (b) 48000 (c) 4800
  34. 34.Best estimate of 26 × 40? (a) 120 (b) 1200 (c) 12000
  35. 35.Best estimate of 70 × 16? (a) 14000 (b) 1400 (c) 140
  36. 36.Best estimate of 13 × 30? (a) 30 (b) 3000 (c) 300
  37. 37.Best estimate of 97 × 59? (a) 6000 (b) 600 (c) 60000
  38. 38.Best estimate of 83 × 24? (a) 1600 (b) 16000 (c) 160
  39. 39.Best estimate of 527 + 844? (a) 1300 (b) 1100 (c) 1500
  40. 40.Best estimate of 195 + 414? (a) 600 (b) 800 (c) 400

Answer key

  1. 700
  2. 2000
  3. 5600
  4. 1200
  5. 4500
  6. 800
  7. 1800
  8. 6300
  9. 7200
  10. 800
  11. 1000
  12. 2800
  13. 4500
  14. 800
  15. 4200
  16. 6400
  17. 2700
  18. 800
  19. 600
  20. 2500
  21. 4000
  22. 800
  23. 2400
  24. 800
  25. 7200
  26. 1000
  27. 900
  28. 3600
  29. 1200
  30. 600
  31. 1100
  32. 9000
  33. 4800
  34. 1200
  35. 1400
  36. 300
  37. 6000
  38. 1600
  39. 1300
  40. 600

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