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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 916 · 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 90 × 77? (a) 72000 (b) 7200 (c) 720
  2. 2.Best estimate of 89 × 27? (a) 2700 (b) 27000 (c) 270
  3. 3.Best estimate of 60 × 36? (a) 2400 (b) 240 (c) 24000
  4. 4.Best estimate of 736 + 724? (a) 1400 (b) 1200 (c) 1600
  5. 5.Best estimate of 352 + 504? (a) 900 (b) 700 (c) 1100
  6. 6.Best estimate of 180 + 719? (a) 900 (b) 700 (c) 1100
  7. 7.Best estimate of 619 + 328? (a) 900 (b) 1100 (c) 700
  8. 8.Best estimate of 41 × 63? (a) 240 (b) 2400 (c) 24000
  9. 9.Best estimate of 343 + 126? (a) 400 (b) 200 (c) 600
  10. 10.Best estimate of 148 + 187? (a) 500 (b) 100 (c) 300
  11. 11.Best estimate of 44 × 31? (a) 12000 (b) 120 (c) 1200
  12. 12.Best estimate of 136 + 211? (a) 500 (b) 300 (c) 100
  13. 13.Best estimate of 654 + 209? (a) 1100 (b) 700 (c) 900
  14. 14.Best estimate of 644 + 230? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 18 × 26? (a) 600 (b) 6000 (c) 60
  16. 16.Best estimate of 87 × 34? (a) 2700 (b) 27000 (c) 270
  17. 17.Best estimate of 23 × 54? (a) 10000 (b) 100 (c) 1000
  18. 18.Best estimate of 19 × 64? (a) 120 (b) 12000 (c) 1200
  19. 19.Best estimate of 56 × 40? (a) 240 (b) 2400 (c) 24000
  20. 20.Best estimate of 311 + 712? (a) 1000 (b) 800 (c) 1200
  21. 21.Best estimate of 395 + 461? (a) 1100 (b) 700 (c) 900
  22. 22.Best estimate of 13 × 74? (a) 700 (b) 7000 (c) 70
  23. 23.Best estimate of 69 × 21? (a) 1400 (b) 14000 (c) 140
  24. 24.Best estimate of 805 + 811? (a) 1800 (b) 1600 (c) 1400
  25. 25.Best estimate of 306 + 480? (a) 600 (b) 1000 (c) 800
  26. 26.Best estimate of 16 × 29? (a) 600 (b) 60 (c) 6000
  27. 27.Best estimate of 96 × 51? (a) 5000 (b) 50000 (c) 500
  28. 28.Best estimate of 174 + 860? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 37 × 68? (a) 2800 (b) 280 (c) 28000
  30. 30.Best estimate of 18 × 44? (a) 8000 (b) 800 (c) 80
  31. 31.Best estimate of 776 + 775? (a) 1600 (b) 1800 (c) 1400
  32. 32.Best estimate of 454 + 693? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 96 × 54? (a) 50000 (b) 5000 (c) 500
  34. 34.Best estimate of 66 × 67? (a) 490 (b) 4900 (c) 49000
  35. 35.Best estimate of 266 + 437? (a) 500 (b) 700 (c) 900
  36. 36.Best estimate of 89 × 54? (a) 4500 (b) 450 (c) 45000
  37. 37.Best estimate of 74 × 36? (a) 28000 (b) 280 (c) 2800
  38. 38.Best estimate of 68 × 96? (a) 7000 (b) 70000 (c) 700
  39. 39.Best estimate of 21 × 64? (a) 12000 (b) 1200 (c) 120
  40. 40.Best estimate of 92 × 47? (a) 450 (b) 4500 (c) 45000

Answer key

  1. 7200
  2. 2700
  3. 2400
  4. 1400
  5. 900
  6. 900
  7. 900
  8. 2400
  9. 400
  10. 300
  11. 1200
  12. 300
  13. 900
  14. 800
  15. 600
  16. 2700
  17. 1000
  18. 1200
  19. 2400
  20. 1000
  21. 900
  22. 700
  23. 1400
  24. 1600
  25. 800
  26. 600
  27. 5000
  28. 1100
  29. 2800
  30. 800
  31. 1600
  32. 1200
  33. 5000
  34. 4900
  35. 700
  36. 4500
  37. 2800
  38. 7000
  39. 1200
  40. 4500

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