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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 117 · 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.Which of these is a perfect cube? (a) 757 (b) 729 (c) 732
  2. 2.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  3. 3.What is ∛13824? =
  4. 4.What is 18³? =
  5. 5.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  6. 6.What is 15³? =
  7. 7.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  8. 8.Which of these is a perfect cube? (a) 173 (b) 190 (c) 125
  9. 9.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  11. 11.What is 13³? =
  12. 12.Which of these is a perfect cube? (a) 512 (b) 550 (c) 545
  13. 13.What is ∛1000? =
  14. 14.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.Which of these is a perfect cube? (a) 1728 (b) 2056 (c) 1811
  16. 16.What is 6³? =
  17. 17.What is ∛343? =
  18. 18.What is ∛27? =
  19. 19.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  20. 20.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  21. 21.What is 10³? =
  22. 22.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  23. 23.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 343 (b) 405 (c) 355
  25. 25.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  26. 26.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  27. 27.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  29. 29.What is 4³? =
  30. 30.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  31. 31.Which of these is a perfect cube? (a) 2702 (b) 2197 (c) 2254
  32. 32.What is 2³? =
  33. 33.What is ∛2197? =
  34. 34.What is 20³? =
  35. 35.What is ∛6859? =
  36. 36.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  37. 37.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  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 the smallest whole number by which 128 must be multiplied to get a perfect cube?
  40. 40.What is ∛4913? =

Answer key

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

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