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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 971 · 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 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  3. 3.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is ∛8000? =
  5. 5.What is ∛1000? =
  6. 6.Which of these is a perfect cube? (a) 90 (b) 64 (c) 108
  7. 7.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  8. 8.Which of these is a perfect cube? (a) 3934 (b) 3375 (c) 3700
  9. 9.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  10. 10.What is 8³? =
  11. 11.What is ∛343? =
  12. 12.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  13. 13.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  14. 14.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  15. 15.What is ∛3375? =
  16. 16.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  17. 17.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  18. 18.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  19. 19.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  20. 20.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  21. 21.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛4096? =
  23. 23.What is 18³? =
  24. 24.What is 15³? =
  25. 25.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  26. 26.What is ∛8? =
  27. 27.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.Which of these is a perfect cube? (a) 1753 (b) 1909 (c) 1728
  30. 30.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  31. 31.What is 13³? =
  32. 32.Which of these is a perfect cube? (a) 33 (b) 31 (c) 27
  33. 33.What is 4³? =
  34. 34.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  35. 35.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  36. 36.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  37. 37.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  38. 38.What is ∛1728? =
  39. 39.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 27
  2. 4
  3. 8
  4. 20
  5. 10
  6. 64
  7. 4
  8. 3375
  9. 3
  10. 512
  11. 7
  12. 2
  13. 27
  14. 15
  15. 15
  16. 7
  17. 3
  18. 9
  19. 49
  20. 16
  21. 8
  22. 16
  23. 5832
  24. 3375
  25. 9
  26. 2
  27. 64
  28. 216
  29. 1728
  30. 5
  31. 2197
  32. 27
  33. 64
  34. 10
  35. 49
  36. 2
  37. 18
  38. 12
  39. 125
  40. 125

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