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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 34 · 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 16 × 62? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 299 + 179? (a) 500 (b) 300 (c) 700
  3. 3.Best estimate of 37 × 19? (a) 80 (b) 800 (c) 8000
  4. 4.Best estimate of 73 × 81? (a) 56000 (b) 5600 (c) 560
  5. 5.Best estimate of 96 × 42? (a) 40000 (b) 4000 (c) 400
  6. 6.Best estimate of 390 + 320? (a) 900 (b) 700 (c) 500
  7. 7.Best estimate of 62 × 66? (a) 4200 (b) 420 (c) 42000
  8. 8.Best estimate of 42 × 26? (a) 120 (b) 12000 (c) 1200
  9. 9.Best estimate of 43 × 22? (a) 80 (b) 8000 (c) 800
  10. 10.Best estimate of 96 × 64? (a) 6000 (b) 600 (c) 60000
  11. 11.Best estimate of 16 × 37? (a) 80 (b) 8000 (c) 800
  12. 12.Best estimate of 61 × 52? (a) 300 (b) 3000 (c) 30000
  13. 13.Best estimate of 87 × 19? (a) 180 (b) 1800 (c) 18000
  14. 14.Best estimate of 88 × 39? (a) 3600 (b) 360 (c) 36000
  15. 15.Best estimate of 73 × 32? (a) 21000 (b) 2100 (c) 210
  16. 16.Best estimate of 27 × 58? (a) 1800 (b) 18000 (c) 180
  17. 17.Best estimate of 12 × 81? (a) 8000 (b) 800 (c) 80
  18. 18.Best estimate of 54 × 24? (a) 1000 (b) 100 (c) 10000
  19. 19.Best estimate of 345 + 562? (a) 1100 (b) 900 (c) 700
  20. 20.Best estimate of 128 + 440? (a) 500 (b) 300 (c) 700
  21. 21.Best estimate of 80 × 86? (a) 7200 (b) 720 (c) 72000
  22. 22.Best estimate of 34 × 16? (a) 600 (b) 60 (c) 6000
  23. 23.Best estimate of 62 × 23? (a) 1200 (b) 120 (c) 12000
  24. 24.Best estimate of 448 + 421? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 12 × 26? (a) 300 (b) 30 (c) 3000
  26. 26.Best estimate of 80 × 21? (a) 1600 (b) 160 (c) 16000
  27. 27.Best estimate of 71 × 20? (a) 14000 (b) 140 (c) 1400
  28. 28.Best estimate of 778 + 228? (a) 1200 (b) 1000 (c) 800
  29. 29.Best estimate of 749 + 862? (a) 1800 (b) 1400 (c) 1600
  30. 30.Best estimate of 49 × 16? (a) 10000 (b) 1000 (c) 100
  31. 31.Best estimate of 778 + 517? (a) 1500 (b) 1300 (c) 1100
  32. 32.Best estimate of 381 + 308? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 571 + 695? (a) 1300 (b) 1500 (c) 1100
  34. 34.Best estimate of 78 × 18? (a) 16000 (b) 1600 (c) 160
  35. 35.Best estimate of 82 × 29? (a) 240 (b) 24000 (c) 2400
  36. 36.Best estimate of 270 + 324? (a) 800 (b) 400 (c) 600
  37. 37.Best estimate of 76 × 98? (a) 800 (b) 8000 (c) 80000
  38. 38.Best estimate of 183 + 321? (a) 300 (b) 500 (c) 700
  39. 39.Best estimate of 21 × 29? (a) 600 (b) 6000 (c) 60
  40. 40.Best estimate of 67 × 66? (a) 490 (b) 4900 (c) 49000

Answer key

  1. 1200
  2. 500
  3. 800
  4. 5600
  5. 4000
  6. 700
  7. 4200
  8. 1200
  9. 800
  10. 6000
  11. 800
  12. 3000
  13. 1800
  14. 3600
  15. 2100
  16. 1800
  17. 800
  18. 1000
  19. 900
  20. 500
  21. 7200
  22. 600
  23. 1200
  24. 800
  25. 300
  26. 1600
  27. 1400
  28. 1000
  29. 1600
  30. 1000
  31. 1300
  32. 700
  33. 1300
  34. 1600
  35. 2400
  36. 600
  37. 8000
  38. 500
  39. 600
  40. 4900

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