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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 649 · 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 70 × 76? (a) 560 (b) 56000 (c) 5600
  2. 2.Best estimate of 495 + 179? (a) 900 (b) 500 (c) 700
  3. 3.Best estimate of 70 × 30? (a) 21000 (b) 210 (c) 2100
  4. 4.Best estimate of 628 + 342? (a) 900 (b) 700 (c) 1100
  5. 5.Best estimate of 56 × 20? (a) 1200 (b) 120 (c) 12000
  6. 6.Best estimate of 659 + 445? (a) 1300 (b) 900 (c) 1100
  7. 7.Best estimate of 52 × 40? (a) 20000 (b) 2000 (c) 200
  8. 8.Best estimate of 16 × 58? (a) 1200 (b) 12000 (c) 120
  9. 9.Best estimate of 53 × 63? (a) 300 (b) 30000 (c) 3000
  10. 10.Best estimate of 72 × 96? (a) 700 (b) 70000 (c) 7000
  11. 11.Best estimate of 67 × 52? (a) 3500 (b) 35000 (c) 350
  12. 12.Best estimate of 51 × 46? (a) 25000 (b) 2500 (c) 250
  13. 13.Best estimate of 14 × 83? (a) 80 (b) 8000 (c) 800
  14. 14.Best estimate of 819 + 382? (a) 1400 (b) 1200 (c) 1000
  15. 15.Best estimate of 37 × 91? (a) 3600 (b) 360 (c) 36000
  16. 16.Best estimate of 175 + 290? (a) 500 (b) 700 (c) 300
  17. 17.Best estimate of 132 + 194? (a) 300 (b) 100 (c) 500
  18. 18.Best estimate of 502 + 149? (a) 800 (b) 600 (c) 400
  19. 19.Best estimate of 880 + 559? (a) 1700 (b) 1500 (c) 1300
  20. 20.Best estimate of 513 + 602? (a) 1300 (b) 1100 (c) 900
  21. 21.Best estimate of 217 + 629? (a) 1000 (b) 800 (c) 600
  22. 22.Best estimate of 77 × 68? (a) 560 (b) 56000 (c) 5600
  23. 23.Best estimate of 18 × 63? (a) 1200 (b) 120 (c) 12000
  24. 24.Best estimate of 227 + 623? (a) 600 (b) 800 (c) 1000
  25. 25.Best estimate of 266 + 267? (a) 800 (b) 600 (c) 400
  26. 26.Best estimate of 63 × 49? (a) 30000 (b) 300 (c) 3000
  27. 27.Best estimate of 644 + 567? (a) 1000 (b) 1200 (c) 1400
  28. 28.Best estimate of 647 + 866? (a) 1300 (b) 1500 (c) 1700
  29. 29.Best estimate of 222 + 380? (a) 800 (b) 600 (c) 400
  30. 30.Best estimate of 30 × 71? (a) 21000 (b) 210 (c) 2100
  31. 31.Best estimate of 22 × 91? (a) 180 (b) 1800 (c) 18000
  32. 32.Best estimate of 21 × 87? (a) 180 (b) 18000 (c) 1800
  33. 33.Best estimate of 339 + 477? (a) 1000 (b) 800 (c) 600
  34. 34.Best estimate of 455 + 529? (a) 800 (b) 1000 (c) 1200
  35. 35.Best estimate of 26 × 27? (a) 90 (b) 9000 (c) 900
  36. 36.Best estimate of 123 + 704? (a) 800 (b) 1000 (c) 600
  37. 37.Best estimate of 230 + 495? (a) 700 (b) 900 (c) 500
  38. 38.Best estimate of 26 × 18? (a) 6000 (b) 600 (c) 60
  39. 39.Best estimate of 78 × 62? (a) 4800 (b) 48000 (c) 480
  40. 40.Best estimate of 417 + 457? (a) 900 (b) 1100 (c) 700

Answer key

  1. 5600
  2. 700
  3. 2100
  4. 900
  5. 1200
  6. 1100
  7. 2000
  8. 1200
  9. 3000
  10. 7000
  11. 3500
  12. 2500
  13. 800
  14. 1200
  15. 3600
  16. 500
  17. 300
  18. 600
  19. 1500
  20. 1100
  21. 800
  22. 5600
  23. 1200
  24. 800
  25. 600
  26. 3000
  27. 1200
  28. 1500
  29. 600
  30. 2100
  31. 1800
  32. 1800
  33. 800
  34. 1000
  35. 900
  36. 800
  37. 700
  38. 600
  39. 4800
  40. 900

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