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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 989 · 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 94 × 74? (a) 630 (b) 6300 (c) 63000
  2. 2.Best estimate of 67 × 82? (a) 560 (b) 56000 (c) 5600
  3. 3.Best estimate of 63 × 62? (a) 36000 (b) 3600 (c) 360
  4. 4.Best estimate of 76 × 76? (a) 6400 (b) 64000 (c) 640
  5. 5.Best estimate of 43 × 23? (a) 800 (b) 80 (c) 8000
  6. 6.Best estimate of 64 × 88? (a) 540 (b) 54000 (c) 5400
  7. 7.Best estimate of 356 + 825? (a) 1200 (b) 1400 (c) 1000
  8. 8.Best estimate of 301 + 870? (a) 1400 (b) 1000 (c) 1200
  9. 9.Best estimate of 261 + 311? (a) 800 (b) 400 (c) 600
  10. 10.Best estimate of 97 × 27? (a) 3000 (b) 30000 (c) 300
  11. 11.Best estimate of 539 + 392? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 379 + 205? (a) 400 (b) 800 (c) 600
  13. 13.Best estimate of 76 × 21? (a) 1600 (b) 16000 (c) 160
  14. 14.Best estimate of 416 + 221? (a) 800 (b) 600 (c) 400
  15. 15.Best estimate of 435 + 835? (a) 1200 (b) 1400 (c) 1000
  16. 16.Best estimate of 515 + 151? (a) 900 (b) 700 (c) 500
  17. 17.Best estimate of 693 + 437? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 66 × 27? (a) 2100 (b) 21000 (c) 210
  19. 19.Best estimate of 81 × 57? (a) 48000 (b) 4800 (c) 480
  20. 20.Best estimate of 20 × 78? (a) 16000 (b) 160 (c) 1600
  21. 21.Best estimate of 162 + 502? (a) 900 (b) 500 (c) 700
  22. 22.Best estimate of 496 + 637? (a) 1100 (b) 900 (c) 1300
  23. 23.Best estimate of 496 + 628? (a) 1100 (b) 900 (c) 1300
  24. 24.Best estimate of 71 × 97? (a) 7000 (b) 70000 (c) 700
  25. 25.Best estimate of 89 × 33? (a) 270 (b) 2700 (c) 27000
  26. 26.Best estimate of 14 × 96? (a) 1000 (b) 100 (c) 10000
  27. 27.Best estimate of 615 + 170? (a) 600 (b) 800 (c) 1000
  28. 28.Best estimate of 38 × 31? (a) 1200 (b) 12000 (c) 120
  29. 29.Best estimate of 133 + 377? (a) 700 (b) 300 (c) 500
  30. 30.Best estimate of 61 × 27? (a) 180 (b) 18000 (c) 1800
  31. 31.Best estimate of 26 × 14? (a) 300 (b) 30 (c) 3000
  32. 32.Best estimate of 12 × 54? (a) 500 (b) 50 (c) 5000
  33. 33.Best estimate of 92 × 26? (a) 2700 (b) 27000 (c) 270
  34. 34.Best estimate of 377 + 215? (a) 800 (b) 400 (c) 600
  35. 35.Best estimate of 64 × 54? (a) 300 (b) 3000 (c) 30000
  36. 36.Best estimate of 43 × 24? (a) 8000 (b) 80 (c) 800
  37. 37.Best estimate of 27 × 68? (a) 2100 (b) 21000 (c) 210
  38. 38.Best estimate of 444 + 156? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 89 × 16? (a) 18000 (b) 180 (c) 1800
  40. 40.Best estimate of 797 + 782? (a) 1600 (b) 1800 (c) 1400

Answer key

  1. 6300
  2. 5600
  3. 3600
  4. 6400
  5. 800
  6. 5400
  7. 1200
  8. 1200
  9. 600
  10. 3000
  11. 900
  12. 600
  13. 1600
  14. 600
  15. 1200
  16. 700
  17. 1100
  18. 2100
  19. 4800
  20. 1600
  21. 700
  22. 1100
  23. 1100
  24. 7000
  25. 2700
  26. 1000
  27. 800
  28. 1200
  29. 500
  30. 1800
  31. 300
  32. 500
  33. 2700
  34. 600
  35. 3000
  36. 800
  37. 2100
  38. 600
  39. 1800
  40. 1600

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