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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 144 · 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 2197 cubic cm. How long is each edge (in cm)?
  2. 2.What is 13³? =
  3. 3.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  4. 4.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  5. 5.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  6. 6.What is 14³? =
  7. 7.What is 17³? =
  8. 8.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  10. 10.What is ∛729? =
  11. 11.What is ∛125? =
  12. 12.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  13. 13.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  14. 14.Which of these is a perfect cube? (a) 931 (b) 729 (c) 756
  15. 15.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 343 (b) 359 (c) 360
  17. 17.What is ∛5832? =
  18. 18.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  19. 19.What is 20³? =
  20. 20.What is 2³? =
  21. 21.What is 18³? =
  22. 22.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  23. 23.What is 5³? =
  24. 24.Which of these is a perfect cube? (a) 2357 (b) 2643 (c) 2197
  25. 25.What is ∛3375? =
  26. 26.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  27. 27.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.Which of these is a perfect cube? (a) 1000 (b) 1161 (c) 1239
  29. 29.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  30. 30.What is 8³? =
  31. 31.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  32. 32.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  33. 33.What is ∛343? =
  34. 34.What is ∛2744? =
  35. 35.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is 15³? =
  38. 38.What is ∛4096? =
  39. 39.What is 12³? =
  40. 40.Which of these is a perfect cube? (a) 27 (b) 28 (c) 36

Answer key

  1. 13
  2. 2197
  3. 3
  4. 2
  5. 15
  6. 2744
  7. 4913
  8. 4
  9. 9
  10. 9
  11. 5
  12. 20
  13. 216
  14. 729
  15. 125
  16. 343
  17. 18
  18. 7
  19. 8000
  20. 8
  21. 5832
  22. 19
  23. 125
  24. 2197
  25. 15
  26. 4
  27. 64
  28. 1000
  29. 4
  30. 512
  31. 7
  32. 6
  33. 7
  34. 14
  35. 8
  36. 64
  37. 3375
  38. 16
  39. 1728
  40. 27

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