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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 71 · 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 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 473 (b) 343 (c) 365
  3. 3.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  4. 4.What is 18³? =
  5. 5.What is ∛4096? =
  6. 6.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  7. 7.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  8. 8.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  9. 9.What is 14³? =
  10. 10.Which of these is a perfect cube? (a) 147 (b) 139 (c) 125
  11. 11.Which of these is a perfect cube? (a) 2197 (b) 2427 (c) 2209
  12. 12.Which of these is a perfect cube? (a) 111 (b) 90 (c) 64
  13. 13.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  15. 15.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  16. 16.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  17. 17.What is ∛15625? =
  18. 18.What is ∛2197? =
  19. 19.What is 17³? =
  20. 20.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  22. 22.What is ∛216? =
  23. 23.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  24. 24.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  25. 25.What is ∛3375? =
  26. 26.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  27. 27.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  30. 30.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  32. 32.What is ∛4913? =
  33. 33.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  34. 34.What is 16³? =
  35. 35.What is 15³? =
  36. 36.What is 13³? =
  37. 37.What is ∛5832? =
  38. 38.What is ∛8? =
  39. 39.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  40. 40.Which of these is a perfect cube? (a) 2122 (b) 1728 (c) 2127

Answer key

  1. 216
  2. 343
  3. 2
  4. 5832
  5. 16
  6. 9
  7. 2
  8. 14
  9. 2744
  10. 125
  11. 2197
  12. 64
  13. 64
  14. 15
  15. 2
  16. 216
  17. 25
  18. 13
  19. 4913
  20. 25
  21. 27
  22. 6
  23. 8
  24. 25
  25. 15
  26. 9
  27. 4
  28. 64
  29. 18
  30. 2
  31. 3
  32. 17
  33. 5
  34. 4096
  35. 3375
  36. 2197
  37. 18
  38. 2
  39. 9
  40. 1728

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