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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 671 · 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 32 must be divided to get a perfect cube?
  2. 2.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  4. 4.What is 2³? =
  5. 5.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.What is the smallest whole number by which 135 must be divided to get a perfect cube?
  7. 7.What is 5³? =
  8. 8.Which of these is a perfect cube? (a) 27 (b) 34 (c) 31
  9. 9.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  10. 10.What is ∛4096? =
  11. 11.What is ∛8000? =
  12. 12.What is 17³? =
  13. 13.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  14. 14.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.What is ∛27? =
  16. 16.What is ∛343? =
  17. 17.What is ∛1728? =
  18. 18.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  19. 19.What is ∛729? =
  20. 20.Which of these is a perfect cube? (a) 3296 (b) 2962 (c) 2744
  21. 21.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  22. 22.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  23. 23.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 729 (b) 846 (c) 778
  25. 25.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  26. 26.What is ∛15625? =
  27. 27.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  28. 28.What is 7³? =
  29. 29.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  30. 30.Which of these is a perfect cube? (a) 2610 (b) 2556 (c) 2197
  31. 31.What is 4³? =
  32. 32.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  33. 33.What is 12³? =
  34. 34.What is 18³? =
  35. 35.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  38. 38.What is 8³? =
  39. 39.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  40. 40.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?

Answer key

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

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