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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 806 · 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 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 125 (b) 199 (c) 151
  3. 3.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  4. 4.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  5. 5.What is ∛1000? =
  6. 6.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  7. 7.What is 13³? =
  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 12³? =
  10. 10.What is ∛8000? =
  11. 11.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  12. 12.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  13. 13.What is ∛13824? =
  14. 14.What is ∛27? =
  15. 15.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  16. 16.What is ∛1331? =
  17. 17.What is 20³? =
  18. 18.What is 8³? =
  19. 19.Which of these is a perfect cube? (a) 1001 (b) 1000 (c) 1038
  20. 20.Which of these is a perfect cube? (a) 675 (b) 679 (c) 512
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  23. 23.What is ∛4913? =
  24. 24.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  25. 25.What is ∛512? =
  26. 26.Which of these is a perfect cube? (a) 2815 (b) 2826 (c) 2744
  27. 27.Which of these is a perfect cube? (a) 111 (b) 109 (c) 64
  28. 28.What is ∛12167? =
  29. 29.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  30. 30.What is ∛1728? =
  31. 31.What is ∛343? =
  32. 32.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  33. 33.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.Which of these is a perfect cube? (a) 343 (b) 458 (c) 347
  35. 35.What is ∛10648? =
  36. 36.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  37. 37.What is 10³? =
  38. 38.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.What is 9³? =
  40. 40.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?

Answer key

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

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