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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 923 · 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 198 + 396? (a) 800 (b) 600 (c) 400
  2. 2.Best estimate of 20 × 12? (a) 200 (b) 20 (c) 2000
  3. 3.Best estimate of 149 + 518? (a) 600 (b) 800 (c) 400
  4. 4.Best estimate of 352 + 506? (a) 1100 (b) 700 (c) 900
  5. 5.Best estimate of 296 + 378? (a) 500 (b) 900 (c) 700
  6. 6.Best estimate of 92 × 49? (a) 4500 (b) 45000 (c) 450
  7. 7.Best estimate of 126 + 853? (a) 1000 (b) 1200 (c) 800
  8. 8.Best estimate of 175 + 631? (a) 800 (b) 600 (c) 1000
  9. 9.Best estimate of 51 × 74? (a) 3500 (b) 350 (c) 35000
  10. 10.Best estimate of 69 × 78? (a) 560 (b) 56000 (c) 5600
  11. 11.Best estimate of 877 + 864? (a) 1800 (b) 2000 (c) 1600
  12. 12.Best estimate of 90 × 86? (a) 81000 (b) 8100 (c) 810
  13. 13.Best estimate of 30 × 38? (a) 1200 (b) 120 (c) 12000
  14. 14.Best estimate of 64 × 97? (a) 6000 (b) 60000 (c) 600
  15. 15.Best estimate of 12 × 12? (a) 100 (b) 10 (c) 1000
  16. 16.Best estimate of 215 + 619? (a) 1000 (b) 800 (c) 600
  17. 17.Best estimate of 80 × 68? (a) 560 (b) 5600 (c) 56000
  18. 18.Best estimate of 91 × 29? (a) 27000 (b) 270 (c) 2700
  19. 19.Best estimate of 87 × 98? (a) 90000 (b) 9000 (c) 900
  20. 20.Best estimate of 90 × 62? (a) 540 (b) 5400 (c) 54000
  21. 21.Best estimate of 81 × 86? (a) 7200 (b) 72000 (c) 720
  22. 22.Best estimate of 74 × 18? (a) 1400 (b) 14000 (c) 140
  23. 23.Best estimate of 67 × 57? (a) 4200 (b) 420 (c) 42000
  24. 24.Best estimate of 26 × 37? (a) 120 (b) 1200 (c) 12000
  25. 25.Best estimate of 256 + 422? (a) 900 (b) 500 (c) 700
  26. 26.Best estimate of 365 + 324? (a) 900 (b) 700 (c) 500
  27. 27.Best estimate of 29 × 53? (a) 15000 (b) 1500 (c) 150
  28. 28.Best estimate of 74 × 88? (a) 6300 (b) 63000 (c) 630
  29. 29.Best estimate of 36 × 69? (a) 2800 (b) 28000 (c) 280
  30. 30.Best estimate of 26 × 98? (a) 300 (b) 30000 (c) 3000
  31. 31.Best estimate of 83 × 31? (a) 240 (b) 2400 (c) 24000
  32. 32.Best estimate of 26 × 47? (a) 1500 (b) 150 (c) 15000
  33. 33.Best estimate of 648 + 216? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 87 × 29? (a) 2700 (b) 27000 (c) 270
  35. 35.Best estimate of 53 × 53? (a) 25000 (b) 250 (c) 2500
  36. 36.Best estimate of 381 + 397? (a) 1000 (b) 600 (c) 800
  37. 37.Best estimate of 16 × 86? (a) 1800 (b) 18000 (c) 180
  38. 38.Best estimate of 27 × 47? (a) 150 (b) 15000 (c) 1500
  39. 39.Best estimate of 456 + 817? (a) 1100 (b) 1300 (c) 1500
  40. 40.Best estimate of 72 × 64? (a) 42000 (b) 420 (c) 4200

Answer key

  1. 600
  2. 200
  3. 600
  4. 900
  5. 700
  6. 4500
  7. 1000
  8. 800
  9. 3500
  10. 5600
  11. 1800
  12. 8100
  13. 1200
  14. 6000
  15. 100
  16. 800
  17. 5600
  18. 2700
  19. 9000
  20. 5400
  21. 7200
  22. 1400
  23. 4200
  24. 1200
  25. 700
  26. 700
  27. 1500
  28. 6300
  29. 2800
  30. 3000
  31. 2400
  32. 1500
  33. 800
  34. 2700
  35. 2500
  36. 800
  37. 1800
  38. 1500
  39. 1300
  40. 4200

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