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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 466 · 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 51 × 22? (a) 10000 (b) 1000 (c) 100
  2. 2.Best estimate of 276 + 222? (a) 700 (b) 300 (c) 500
  3. 3.Best estimate of 26 × 52? (a) 150 (b) 15000 (c) 1500
  4. 4.Best estimate of 83 × 87? (a) 720 (b) 7200 (c) 72000
  5. 5.Best estimate of 704 + 791? (a) 1700 (b) 1300 (c) 1500
  6. 6.Best estimate of 36 × 93? (a) 36000 (b) 360 (c) 3600
  7. 7.Best estimate of 59 × 93? (a) 54000 (b) 540 (c) 5400
  8. 8.Best estimate of 837 + 684? (a) 1700 (b) 1300 (c) 1500
  9. 9.Best estimate of 161 + 306? (a) 500 (b) 700 (c) 300
  10. 10.Best estimate of 26 × 70? (a) 2100 (b) 21000 (c) 210
  11. 11.Best estimate of 37 × 19? (a) 80 (b) 8000 (c) 800
  12. 12.Best estimate of 33 × 90? (a) 270 (b) 27000 (c) 2700
  13. 13.Best estimate of 78 × 24? (a) 16000 (b) 1600 (c) 160
  14. 14.Best estimate of 57 × 18? (a) 12000 (b) 120 (c) 1200
  15. 15.Best estimate of 189 + 287? (a) 300 (b) 500 (c) 700
  16. 16.Best estimate of 646 + 253? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 56 × 51? (a) 300 (b) 30000 (c) 3000
  18. 18.Best estimate of 44 × 66? (a) 280 (b) 28000 (c) 2800
  19. 19.Best estimate of 235 + 390? (a) 400 (b) 600 (c) 800
  20. 20.Best estimate of 636 + 266? (a) 700 (b) 900 (c) 1100
  21. 21.Best estimate of 81 × 28? (a) 2400 (b) 240 (c) 24000
  22. 22.Best estimate of 74 × 62? (a) 42000 (b) 4200 (c) 420
  23. 23.Best estimate of 74 × 41? (a) 2800 (b) 280 (c) 28000
  24. 24.Best estimate of 587 + 541? (a) 900 (b) 1300 (c) 1100
  25. 25.Best estimate of 83 × 24? (a) 1600 (b) 16000 (c) 160
  26. 26.Best estimate of 738 + 129? (a) 1000 (b) 800 (c) 600
  27. 27.Best estimate of 132 + 264? (a) 200 (b) 400 (c) 600
  28. 28.Best estimate of 96 × 43? (a) 400 (b) 40000 (c) 4000
  29. 29.Best estimate of 50 × 19? (a) 10000 (b) 1000 (c) 100
  30. 30.Best estimate of 38 × 34? (a) 12000 (b) 1200 (c) 120
  31. 31.Best estimate of 599 + 798? (a) 1400 (b) 1200 (c) 1600
  32. 32.Best estimate of 50 × 51? (a) 25000 (b) 2500 (c) 250
  33. 33.Best estimate of 17 × 62? (a) 1200 (b) 120 (c) 12000
  34. 34.Best estimate of 76 × 74? (a) 5600 (b) 560 (c) 56000
  35. 35.Best estimate of 93 × 36? (a) 3600 (b) 36000 (c) 360
  36. 36.Best estimate of 625 + 479? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 580 + 487? (a) 1100 (b) 900 (c) 1300
  38. 38.Best estimate of 76 × 87? (a) 72000 (b) 720 (c) 7200
  39. 39.Best estimate of 552 + 249? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 126 + 394? (a) 500 (b) 300 (c) 700

Answer key

  1. 1000
  2. 500
  3. 1500
  4. 7200
  5. 1500
  6. 3600
  7. 5400
  8. 1500
  9. 500
  10. 2100
  11. 800
  12. 2700
  13. 1600
  14. 1200
  15. 500
  16. 900
  17. 3000
  18. 2800
  19. 600
  20. 900
  21. 2400
  22. 4200
  23. 2800
  24. 1100
  25. 1600
  26. 800
  27. 400
  28. 4000
  29. 1000
  30. 1200
  31. 1400
  32. 2500
  33. 1200
  34. 5600
  35. 3600
  36. 1100
  37. 1100
  38. 7200
  39. 800
  40. 500

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