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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 626 · 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 ∛8000? =
  2. 2.What is ∛3375? =
  3. 3.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  4. 4.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  5. 5.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  6. 6.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  7. 7.What is ∛13824? =
  8. 8.What is ∛512? =
  9. 9.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  10. 10.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  11. 11.What is 12³? =
  12. 12.What is 15³? =
  13. 13.A big cube of edge 9 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 448 must be multiplied to get a perfect cube?
  15. 15.What is 2³? =
  16. 16.What is ∛9261? =
  17. 17.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  18. 18.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  19. 19.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  20. 20.Which of these is a perfect cube? (a) 2744 (b) 3081 (c) 3281
  21. 21.Which of these is a perfect cube? (a) 393 (b) 441 (c) 343
  22. 22.What is ∛5832? =
  23. 23.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  24. 24.What is ∛2197? =
  25. 25.What is 14³? =
  26. 26.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  27. 27.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  28. 28.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  29. 29.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  30. 30.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  31. 31.What is 13³? =
  32. 32.What is 17³? =
  33. 33.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.What is ∛4913? =
  35. 35.What is ∛10648? =
  36. 36.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  37. 37.What is 7³? =
  38. 38.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  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 729 cubic cm. How long is each edge (in cm)?

Answer key

  1. 20
  2. 15
  3. 4
  4. 2
  5. 25
  6. 15
  7. 24
  8. 8
  9. 17
  10. 20
  11. 1728
  12. 3375
  13. 27
  14. 49
  15. 8
  16. 21
  17. 27
  18. 16
  19. 2
  20. 2744
  21. 343
  22. 18
  23. 8
  24. 13
  25. 2744
  26. 27
  27. 7
  28. 9
  29. 7
  30. 125
  31. 2197
  32. 4913
  33. 125
  34. 17
  35. 22
  36. 5
  37. 343
  38. 11
  39. 25
  40. 9

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