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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 945 · 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.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  2. 2.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  3. 3.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  4. 4.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  5. 5.What is 13³? =
  6. 6.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  7. 7.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  8. 8.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  10. 10.Which of these is a perfect cube? (a) 761 (b) 729 (c) 874
  11. 11.What is 8³? =
  12. 12.What is ∛15625? =
  13. 13.Which of these is a perfect cube? (a) 512 (b) 567 (c) 606
  14. 14.Which of these is a perfect cube? (a) 343 (b) 390 (c) 402
  15. 15.What is 3³? =
  16. 16.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  17. 17.Which of these is a perfect cube? (a) 3057 (b) 2765 (c) 2744
  18. 18.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  19. 19.What is ∛216? =
  20. 20.Which of these is a perfect cube? (a) 261 (b) 216 (c) 251
  21. 21.What is ∛13824? =
  22. 22.What is 6³? =
  23. 23.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  24. 24.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  25. 25.Which of these is a perfect cube? (a) 64 (b) 77 (c) 82
  26. 26.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  27. 27.What is 12³? =
  28. 28.A big cube of edge 3 cm is cut into small cubes of edge 1 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 4³? =
  31. 31.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  32. 32.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  33. 33.What is ∛27? =
  34. 34.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  36. 36.What is ∛8? =
  37. 37.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  38. 38.What is ∛4096? =
  39. 39.What is 17³? =
  40. 40.What is the smallest whole number by which 54 must be divided to get a perfect cube?

Answer key

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

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