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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 69 · 40 sums
TalentJR

The method (Threes make cubes): Cube: n × n × n. Cube root: the number that, used three times, gives the cube. Units digits: 1→1, 2→8, 3→7, 4→4, 5→5, 6→6, 7→3, 8→2, 9→9, 0→0 — use them to guess cube roots. Make a perfect cube: break into primes; multiply by what completes each group of three (or divide by what is left over). A big cube of edge a cut into small cubes of edge b gives (a ÷ b)³ small cubes.

NameDateTime takenScore ___ / 40
  1. 1.What is 9³? =
  2. 2.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  3. 3.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  4. 4.What is ∛1728? =
  5. 5.What is ∛8? =
  6. 6.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  7. 7.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  8. 8.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  9. 9.What is ∛2197? =
  10. 10.What is ∛1331? =
  11. 11.What is 11³? =
  12. 12.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  13. 13.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  14. 14.Which of these is a perfect cube? (a) 3375 (b) 3440 (c) 3775
  15. 15.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  16. 16.What is ∛512? =
  17. 17.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  19. 19.Which of these is a perfect cube? (a) 1419 (b) 1331 (c) 1614
  20. 20.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  21. 21.What is 10³? =
  22. 22.What is ∛8000? =
  23. 23.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  24. 24.What is 14³? =
  25. 25.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  26. 26.Which of these is a perfect cube? (a) 1266 (b) 1000 (c) 1247
  27. 27.What is ∛13824? =
  28. 28.Which of these is a perfect cube? (a) 31 (b) 35 (c) 27
  29. 29.Which of these is a perfect cube? (a) 245 (b) 266 (c) 216
  30. 30.What is 3³? =
  31. 31.Which of these is a perfect cube? (a) 343 (b) 437 (c) 379
  32. 32.What is 15³? =
  33. 33.Which of these is a perfect cube? (a) 921 (b) 968 (c) 729
  34. 34.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  35. 35.What is 2³? =
  36. 36.What is 5³? =
  37. 37.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  38. 38.What is ∛64? =
  39. 39.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  40. 40.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 729
  2. 11
  3. 2
  4. 12
  5. 2
  6. 9
  7. 5
  8. 49
  9. 13
  10. 11
  11. 1331
  12. 9
  13. 4
  14. 3375
  15. 25
  16. 8
  17. 27
  18. 19
  19. 1331
  20. 2
  21. 1000
  22. 20
  23. 5
  24. 2744
  25. 216
  26. 1000
  27. 24
  28. 27
  29. 216
  30. 27
  31. 343
  32. 3375
  33. 729
  34. 27
  35. 8
  36. 125
  37. 216
  38. 4
  39. 4
  40. 125

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