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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 892 · 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 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  3. 3.Which of these is a perfect cube? (a) 136 (b) 125 (c) 170
  4. 4.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  5. 5.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  6. 6.What is ∛13824? =
  7. 7.What is ∛1331? =
  8. 8.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  10. 10.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  11. 11.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  12. 12.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.Which of these is a perfect cube? (a) 1000 (b) 1112 (c) 1125
  14. 14.Which of these is a perfect cube? (a) 2083 (b) 1728 (c) 1887
  15. 15.What is ∛343? =
  16. 16.What is ∛3375? =
  17. 17.Which of these is a perfect cube? (a) 83 (b) 64 (c) 72
  18. 18.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  19. 19.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  21. 21.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛729? =
  23. 23.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 549 (b) 512 (c) 701
  25. 25.What is ∛2744? =
  26. 26.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.Which of these is a perfect cube? (a) 355 (b) 413 (c) 343
  28. 28.What is 4³? =
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.What is 6³? =
  31. 31.What is 20³? =
  32. 32.What is 12³? =
  33. 33.What is ∛125? =
  34. 34.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  35. 35.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  37. 37.Which of these is a perfect cube? (a) 2414 (b) 2430 (c) 2197
  38. 38.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  39. 39.Which of these is a perfect cube? (a) 33 (b) 27 (c) 39
  40. 40.What is ∛4096? =

Answer key

  1. 27
  2. 11
  3. 125
  4. 5
  5. 7
  6. 24
  7. 11
  8. 216
  9. 9
  10. 18
  11. 3
  12. 27
  13. 1000
  14. 1728
  15. 7
  16. 15
  17. 64
  18. 6
  19. 64
  20. 8
  21. 5
  22. 9
  23. 7
  24. 512
  25. 14
  26. 8
  27. 343
  28. 64
  29. 216
  30. 216
  31. 8000
  32. 1728
  33. 5
  34. 125
  35. 25
  36. 3
  37. 2197
  38. 17
  39. 27
  40. 16

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