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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 137 · 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 57 × 16? (a) 12000 (b) 1200 (c) 120
  2. 2.Best estimate of 617 + 324? (a) 1100 (b) 900 (c) 700
  3. 3.Best estimate of 331 + 639? (a) 900 (b) 700 (c) 1100
  4. 4.Best estimate of 48 × 46? (a) 2500 (b) 250 (c) 25000
  5. 5.Best estimate of 63 × 91? (a) 5400 (b) 540 (c) 54000
  6. 6.Best estimate of 38 × 22? (a) 800 (b) 8000 (c) 80
  7. 7.Best estimate of 834 + 851? (a) 1500 (b) 1700 (c) 1900
  8. 8.Best estimate of 768 + 298? (a) 1300 (b) 900 (c) 1100
  9. 9.Best estimate of 40 × 82? (a) 3200 (b) 32000 (c) 320
  10. 10.Best estimate of 97 × 34? (a) 3000 (b) 300 (c) 30000
  11. 11.Best estimate of 305 + 204? (a) 300 (b) 700 (c) 500
  12. 12.Best estimate of 32 × 81? (a) 240 (b) 2400 (c) 24000
  13. 13.Best estimate of 38 × 83? (a) 3200 (b) 32000 (c) 320
  14. 14.Best estimate of 233 + 489? (a) 700 (b) 500 (c) 900
  15. 15.Best estimate of 41 × 76? (a) 32000 (b) 3200 (c) 320
  16. 16.Best estimate of 198 + 868? (a) 900 (b) 1100 (c) 1300
  17. 17.Best estimate of 617 + 309? (a) 1100 (b) 700 (c) 900
  18. 18.Best estimate of 76 × 33? (a) 24000 (b) 2400 (c) 240
  19. 19.Best estimate of 66 × 32? (a) 2100 (b) 210 (c) 21000
  20. 20.Best estimate of 91 × 47? (a) 45000 (b) 450 (c) 4500
  21. 21.Best estimate of 244 + 549? (a) 500 (b) 700 (c) 900
  22. 22.Best estimate of 32 × 24? (a) 6000 (b) 60 (c) 600
  23. 23.Best estimate of 16 × 79? (a) 1600 (b) 160 (c) 16000
  24. 24.Best estimate of 465 + 614? (a) 1300 (b) 900 (c) 1100
  25. 25.Best estimate of 74 × 74? (a) 49000 (b) 4900 (c) 490
  26. 26.Best estimate of 317 + 129? (a) 600 (b) 400 (c) 200
  27. 27.Best estimate of 53 × 70? (a) 3500 (b) 35000 (c) 350
  28. 28.Best estimate of 877 + 344? (a) 1000 (b) 1200 (c) 1400
  29. 29.Best estimate of 14 × 92? (a) 9000 (b) 900 (c) 90
  30. 30.Best estimate of 821 + 416? (a) 1000 (b) 1400 (c) 1200
  31. 31.Best estimate of 83 × 77? (a) 64000 (b) 640 (c) 6400
  32. 32.Best estimate of 209 + 621? (a) 800 (b) 1000 (c) 600
  33. 33.Best estimate of 420 + 291? (a) 700 (b) 500 (c) 900
  34. 34.Best estimate of 245 + 473? (a) 500 (b) 900 (c) 700
  35. 35.Best estimate of 42 × 62? (a) 240 (b) 2400 (c) 24000
  36. 36.Best estimate of 74 × 44? (a) 28000 (b) 2800 (c) 280
  37. 37.Best estimate of 612 + 312? (a) 1100 (b) 700 (c) 900
  38. 38.Best estimate of 48 × 18? (a) 10000 (b) 100 (c) 1000
  39. 39.Best estimate of 78 × 30? (a) 2400 (b) 24000 (c) 240
  40. 40.Best estimate of 752 + 409? (a) 1200 (b) 1400 (c) 1000

Answer key

  1. 1200
  2. 900
  3. 900
  4. 2500
  5. 5400
  6. 800
  7. 1700
  8. 1100
  9. 3200
  10. 3000
  11. 500
  12. 2400
  13. 3200
  14. 700
  15. 3200
  16. 1100
  17. 900
  18. 2400
  19. 2100
  20. 4500
  21. 700
  22. 600
  23. 1600
  24. 1100
  25. 4900
  26. 400
  27. 3500
  28. 1200
  29. 900
  30. 1200
  31. 6400
  32. 800
  33. 700
  34. 700
  35. 2400
  36. 2800
  37. 900
  38. 1000
  39. 2400
  40. 1200

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