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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 866 · 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.What is ∛3375? =
  3. 3.What is ∛15625? =
  4. 4.What is ∛125? =
  5. 5.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 1349 (b) 1331 (c) 1428
  7. 7.Which of these is a perfect cube? (a) 146 (b) 145 (c) 125
  8. 8.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  9. 9.What is ∛13824? =
  10. 10.What is ∛8? =
  11. 11.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  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 8³? =
  14. 14.What is ∛1728? =
  15. 15.What is 13³? =
  16. 16.Which of these is a perfect cube? (a) 3379 (b) 3733 (c) 3375
  17. 17.Which of these is a perfect cube? (a) 1033 (b) 1107 (c) 1000
  18. 18.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  19. 19.What is 18³? =
  20. 20.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  21. 21.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  22. 22.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  23. 23.What is 4³? =
  24. 24.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  25. 25.Which of these is a perfect cube? (a) 2744 (b) 3289 (c) 3317
  26. 26.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  28. 28.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  30. 30.What is 7³? =
  31. 31.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  32. 32.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  33. 33.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  35. 35.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.What is ∛8000? =
  37. 37.What is ∛6859? =
  38. 38.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  39. 39.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?

Answer key

  1. 216
  2. 15
  3. 25
  4. 5
  5. 27
  6. 1331
  7. 125
  8. 5
  9. 24
  10. 2
  11. 3
  12. 125
  13. 512
  14. 12
  15. 2197
  16. 3375
  17. 1000
  18. 2
  19. 5832
  20. 4
  21. 8
  22. 19
  23. 64
  24. 4
  25. 2744
  26. 64
  27. 2
  28. 64
  29. 2
  30. 343
  31. 6
  32. 8
  33. 216
  34. 14
  35. 27
  36. 20
  37. 19
  38. 5
  39. 49
  40. 13

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