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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 711 · 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 8000 cubic cm. How long is each edge (in cm)?
  2. 2.What is 12³? =
  3. 3.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  4. 4.What is 13³? =
  5. 5.Which of these is a perfect cube? (a) 1216 (b) 1000 (c) 1184
  6. 6.Which of these is a perfect cube? (a) 191 (b) 197 (c) 125
  7. 7.What is 14³? =
  8. 8.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  9. 9.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  10. 10.Which of these is a perfect cube? (a) 3434 (b) 3375 (c) 3593
  11. 11.What is ∛512? =
  12. 12.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  14. 14.Which of these is a perfect cube? (a) 1932 (b) 1920 (c) 1728
  15. 15.What is 18³? =
  16. 16.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  17. 17.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.What is 20³? =
  19. 19.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is ∛8? =
  21. 21.What is 5³? =
  22. 22.What is ∛1728? =
  23. 23.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 686 (b) 512 (c) 541
  25. 25.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  26. 26.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  27. 27.What is 2³? =
  28. 28.What is 15³? =
  29. 29.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  30. 30.Which of these is a perfect cube? (a) 477 (b) 432 (c) 343
  31. 31.What is ∛9261? =
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.What is 17³? =
  34. 34.What is ∛125? =
  35. 35.What is ∛4913? =
  36. 36.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is ∛729? =
  38. 38.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  39. 39.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  40. 40.What is ∛12167? =

Answer key

  1. 20
  2. 1728
  3. 3
  4. 2197
  5. 1000
  6. 125
  7. 2744
  8. 3
  9. 2
  10. 3375
  11. 8
  12. 125
  13. 3
  14. 1728
  15. 5832
  16. 27
  17. 64
  18. 8000
  19. 8
  20. 2
  21. 125
  22. 12
  23. 25
  24. 512
  25. 27
  26. 2
  27. 8
  28. 3375
  29. 2
  30. 343
  31. 21
  32. 27
  33. 4913
  34. 5
  35. 17
  36. 216
  37. 9
  38. 25
  39. 16
  40. 23

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