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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 917 · 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 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  3. 3.What is ∛512? =
  4. 4.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  5. 5.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  6. 6.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  7. 7.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  8. 8.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.What is 16³? =
  10. 10.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  11. 11.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.What is 4³? =
  13. 13.What is ∛1728? =
  14. 14.Which of these is a perfect cube? (a) 729 (b) 910 (c) 775
  15. 15.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  16. 16.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  17. 17.What is 17³? =
  18. 18.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  20. 20.What is ∛125? =
  21. 21.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  22. 22.What is ∛64? =
  23. 23.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  24. 24.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  25. 25.What is 3³? =
  26. 26.Which of these is a perfect cube? (a) 1006 (b) 1000 (c) 1146
  27. 27.What is ∛8000? =
  28. 28.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is ∛27? =
  30. 30.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  31. 31.What is ∛10648? =
  32. 32.What is ∛1331? =
  33. 33.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  34. 34.What is 5³? =
  35. 35.What is ∛8? =
  36. 36.Which of these is a perfect cube? (a) 357 (b) 413 (c) 343
  37. 37.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  39. 39.What is ∛729? =
  40. 40.Which of these is a perfect cube? (a) 2037 (b) 1815 (c) 1728

Answer key

  1. 64
  2. 6
  3. 8
  4. 7
  5. 9
  6. 17
  7. 20
  8. 27
  9. 4096
  10. 4
  11. 27
  12. 64
  13. 12
  14. 729
  15. 3
  16. 2
  17. 4913
  18. 216
  19. 125
  20. 5
  21. 7
  22. 4
  23. 27
  24. 49
  25. 27
  26. 1000
  27. 20
  28. 64
  29. 3
  30. 125
  31. 22
  32. 11
  33. 7
  34. 125
  35. 2
  36. 343
  37. 8
  38. 7
  39. 9
  40. 1728

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