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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 567 · 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 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  2. 2.What is 16³? =
  3. 3.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  4. 4.Which of these is a perfect cube? (a) 40 (b) 27 (c) 47
  5. 5.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  6. 6.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  7. 7.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.What is 5³? =
  9. 9.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  10. 10.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  11. 11.What is 3³? =
  12. 12.What is 8³? =
  13. 13.What is ∛27? =
  14. 14.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is ∛2744? =
  16. 16.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  17. 17.Which of these is a perfect cube? (a) 2744 (b) 3063 (c) 2910
  18. 18.What is 9³? =
  19. 19.Which of these is a perfect cube? (a) 512 (b) 687 (c) 623
  20. 20.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  21. 21.What is ∛2197? =
  22. 22.What is 14³? =
  23. 23.Which of these is a perfect cube? (a) 387 (b) 384 (c) 343
  24. 24.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  25. 25.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  26. 26.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  27. 27.Which of these is a perfect cube? (a) 169 (b) 125 (c) 188
  28. 28.What is 17³? =
  29. 29.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  30. 30.What is 20³? =
  31. 31.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  32. 32.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  33. 33.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  34. 34.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  35. 35.What is ∛8? =
  36. 36.What is 10³? =
  37. 37.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  38. 38.What is ∛729? =
  39. 39.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  40. 40.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?

Answer key

  1. 27
  2. 4096
  3. 5
  4. 27
  5. 4
  6. 64
  7. 64
  8. 125
  9. 18
  10. 64
  11. 27
  12. 512
  13. 3
  14. 125
  15. 14
  16. 2
  17. 2744
  18. 729
  19. 512
  20. 2
  21. 13
  22. 2744
  23. 343
  24. 15
  25. 8
  26. 4
  27. 125
  28. 4913
  29. 4
  30. 8000
  31. 2
  32. 10
  33. 5
  34. 2
  35. 2
  36. 1000
  37. 8
  38. 9
  39. 25
  40. 14

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