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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 737 · 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.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  3. 3.Which of these is a perfect cube? (a) 937 (b) 819 (c) 729
  4. 4.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  5. 5.What is ∛4096? =
  6. 6.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  7. 7.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  8. 8.What is ∛125? =
  9. 9.Which of these is a perfect cube? (a) 27 (b) 46 (c) 28
  10. 10.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  11. 11.What is ∛4913? =
  12. 12.What is 12³? =
  13. 13.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  14. 14.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  15. 15.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  16. 16.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  17. 17.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  18. 18.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  19. 19.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  20. 20.Which of these is a perfect cube? (a) 1807 (b) 1728 (c) 1853
  21. 21.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is 17³? =
  23. 23.What is ∛6859? =
  24. 24.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  25. 25.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  26. 26.What is 5³? =
  27. 27.What is ∛64? =
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  30. 30.What is ∛1000? =
  31. 31.Which of these is a perfect cube? (a) 350 (b) 463 (c) 343
  32. 32.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  33. 33.What is ∛8000? =
  34. 34.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  35. 35.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.What is ∛729? =
  37. 37.What is ∛343? =
  38. 38.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  39. 39.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  40. 40.What is 2³? =

Answer key

  1. 8
  2. 18
  3. 729
  4. 2
  5. 16
  6. 6
  7. 17
  8. 5
  9. 27
  10. 4
  11. 17
  12. 1728
  13. 64
  14. 49
  15. 3
  16. 12
  17. 49
  18. 3
  19. 64
  20. 1728
  21. 216
  22. 4913
  23. 19
  24. 2
  25. 8
  26. 125
  27. 4
  28. 27
  29. 2
  30. 10
  31. 343
  32. 25
  33. 20
  34. 9
  35. 125
  36. 9
  37. 7
  38. 4
  39. 4
  40. 8

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