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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 421 · 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 10584 must be divided to get a perfect cube?
  2. 2.What is 11³? =
  3. 3.What is 15³? =
  4. 4.What is 16³? =
  5. 5.What is ∛343? =
  6. 6.What is 20³? =
  7. 7.A big cube of edge 12 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) 377 (b) 438 (c) 343
  9. 9.What is 9³? =
  10. 10.What is 4³? =
  11. 11.Which of these is a perfect cube? (a) 512 (b) 598 (c) 660
  12. 12.What is ∛64? =
  13. 13.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  14. 14.What is ∛512? =
  15. 15.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  16. 16.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  17. 17.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  18. 18.What is ∛12167? =
  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 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  21. 21.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  23. 23.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  24. 24.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  25. 25.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  26. 26.What is ∛27? =
  27. 27.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  28. 28.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  29. 29.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  31. 31.What is 3³? =
  32. 32.What is ∛2744? =
  33. 33.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  34. 34.What is ∛4913? =
  35. 35.What is 2³? =
  36. 36.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  37. 37.Which of these is a perfect cube? (a) 1728 (b) 2014 (c) 2084
  38. 38.What is ∛8? =
  39. 39.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?

Answer key

  1. 49
  2. 1331
  3. 3375
  4. 4096
  5. 7
  6. 8000
  7. 27
  8. 343
  9. 729
  10. 64
  11. 512
  12. 4
  13. 2
  14. 8
  15. 6
  16. 2
  17. 2
  18. 23
  19. 5
  20. 216
  21. 64
  22. 8
  23. 49
  24. 4
  25. 8
  26. 3
  27. 4
  28. 11
  29. 64
  30. 20
  31. 27
  32. 14
  33. 17
  34. 17
  35. 8
  36. 2
  37. 1728
  38. 2
  39. 18
  40. 4

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