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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 705 · 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 36 × 56? (a) 2400 (b) 240 (c) 24000
  2. 2.Best estimate of 82 × 67? (a) 5600 (b) 56000 (c) 560
  3. 3.Best estimate of 129 + 167? (a) 100 (b) 300 (c) 500
  4. 4.Best estimate of 46 × 81? (a) 4000 (b) 40000 (c) 400
  5. 5.Best estimate of 98 × 36? (a) 4000 (b) 400 (c) 40000
  6. 6.Best estimate of 53 × 79? (a) 40000 (b) 400 (c) 4000
  7. 7.Best estimate of 81 × 17? (a) 160 (b) 1600 (c) 16000
  8. 8.Best estimate of 66 × 17? (a) 1400 (b) 140 (c) 14000
  9. 9.Best estimate of 503 + 172? (a) 900 (b) 700 (c) 500
  10. 10.Best estimate of 81 × 51? (a) 400 (b) 4000 (c) 40000
  11. 11.Best estimate of 41 × 22? (a) 8000 (b) 80 (c) 800
  12. 12.Best estimate of 831 + 325? (a) 1300 (b) 900 (c) 1100
  13. 13.Best estimate of 775 + 762? (a) 1400 (b) 1800 (c) 1600
  14. 14.Best estimate of 72 × 46? (a) 3500 (b) 35000 (c) 350
  15. 15.Best estimate of 28 × 92? (a) 270 (b) 27000 (c) 2700
  16. 16.Best estimate of 620 + 327? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 212 + 642? (a) 800 (b) 1000 (c) 600
  18. 18.Best estimate of 306 + 193? (a) 500 (b) 300 (c) 700
  19. 19.Best estimate of 48 × 20? (a) 100 (b) 1000 (c) 10000
  20. 20.Best estimate of 592 + 684? (a) 1500 (b) 1100 (c) 1300
  21. 21.Best estimate of 80 × 39? (a) 320 (b) 3200 (c) 32000
  22. 22.Best estimate of 44 × 66? (a) 28000 (b) 280 (c) 2800
  23. 23.Best estimate of 427 + 842? (a) 1200 (b) 1000 (c) 1400
  24. 24.Best estimate of 801 + 718? (a) 1300 (b) 1700 (c) 1500
  25. 25.Best estimate of 370 + 760? (a) 1000 (b) 1400 (c) 1200
  26. 26.Best estimate of 27 × 88? (a) 270 (b) 2700 (c) 27000
  27. 27.Best estimate of 362 + 538? (a) 700 (b) 900 (c) 1100
  28. 28.Best estimate of 509 + 467? (a) 800 (b) 1200 (c) 1000
  29. 29.Best estimate of 71 × 16? (a) 14000 (b) 1400 (c) 140
  30. 30.Best estimate of 36 × 33? (a) 1200 (b) 12000 (c) 120
  31. 31.Best estimate of 59 × 83? (a) 480 (b) 48000 (c) 4800
  32. 32.Best estimate of 222 + 416? (a) 600 (b) 800 (c) 400
  33. 33.Best estimate of 53 × 56? (a) 3000 (b) 30000 (c) 300
  34. 34.Best estimate of 351 + 213? (a) 400 (b) 600 (c) 800
  35. 35.Best estimate of 629 + 294? (a) 700 (b) 900 (c) 1100
  36. 36.Best estimate of 96 × 19? (a) 20000 (b) 200 (c) 2000
  37. 37.Best estimate of 158 + 764? (a) 1200 (b) 800 (c) 1000
  38. 38.Best estimate of 46 × 89? (a) 450 (b) 4500 (c) 45000
  39. 39.Best estimate of 144 + 440? (a) 700 (b) 500 (c) 300
  40. 40.Best estimate of 136 + 844? (a) 700 (b) 900 (c) 1100

Answer key

  1. 2400
  2. 5600
  3. 300
  4. 4000
  5. 4000
  6. 4000
  7. 1600
  8. 1400
  9. 700
  10. 4000
  11. 800
  12. 1100
  13. 1600
  14. 3500
  15. 2700
  16. 900
  17. 800
  18. 500
  19. 1000
  20. 1300
  21. 3200
  22. 2800
  23. 1200
  24. 1500
  25. 1200
  26. 2700
  27. 900
  28. 1000
  29. 1400
  30. 1200
  31. 4800
  32. 600
  33. 3000
  34. 600
  35. 900
  36. 2000
  37. 1000
  38. 4500
  39. 500
  40. 900

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