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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 18 · 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 cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  2. 2.Which of these is a perfect cube? (a) 52 (b) 41 (c) 27
  3. 3.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is ∛216? =
  5. 5.Which of these is a perfect cube? (a) 695 (b) 512 (c) 665
  6. 6.What is 5³? =
  7. 7.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  8. 8.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  9. 9.Which of these is a perfect cube? (a) 804 (b) 898 (c) 729
  10. 10.What is 15³? =
  11. 11.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  12. 12.What is 4³? =
  13. 13.Which of these is a perfect cube? (a) 344 (b) 343 (c) 405
  14. 14.What is ∛10648? =
  15. 15.What is 20³? =
  16. 16.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  17. 17.What is 8³? =
  18. 18.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  20. 20.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  21. 21.What is ∛343? =
  22. 22.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  23. 23.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  24. 24.What is ∛64? =
  25. 25.What is 13³? =
  26. 26.What is ∛27? =
  27. 27.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  28. 28.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  29. 29.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  30. 30.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  31. 31.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  32. 32.Which of these is a perfect cube? (a) 2197 (b) 2367 (c) 2204
  33. 33.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  34. 34.What is 10³? =
  35. 35.What is ∛2744? =
  36. 36.What is ∛15625? =
  37. 37.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  39. 39.What is 18³? =
  40. 40.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 14
  2. 27
  3. 8
  4. 6
  5. 512
  6. 125
  7. 9
  8. 3
  9. 729
  10. 3375
  11. 25
  12. 64
  13. 343
  14. 22
  15. 8000
  16. 4
  17. 512
  18. 125
  19. 10
  20. 7
  21. 7
  22. 9
  23. 3
  24. 4
  25. 2197
  26. 3
  27. 17
  28. 12
  29. 2
  30. 7
  31. 8
  32. 2197
  33. 25
  34. 1000
  35. 14
  36. 25
  37. 2
  38. 7
  39. 5832
  40. 64

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