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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 886 · 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 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.What is 7³? =
  3. 3.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  4. 4.Which of these is a perfect cube? (a) 666 (b) 596 (c) 512
  5. 5.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  6. 6.What is ∛5832? =
  7. 7.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  8. 8.What is ∛3375? =
  9. 9.What is 17³? =
  10. 10.What is 14³? =
  11. 11.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  12. 12.What is 5³? =
  13. 13.What is ∛27? =
  14. 14.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  16. 16.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  17. 17.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  18. 18.What is ∛13824? =
  19. 19.What is 3³? =
  20. 20.What is 9³? =
  21. 21.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  22. 22.Which of these is a perfect cube? (a) 1476 (b) 1362 (c) 1331
  23. 23.Which of these is a perfect cube? (a) 1728 (b) 1942 (c) 1764
  24. 24.What is ∛343? =
  25. 25.What is 2³? =
  26. 26.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  27. 27.What is ∛8000? =
  28. 28.Which of these is a perfect cube? (a) 1008 (b) 1082 (c) 1000
  29. 29.What is 18³? =
  30. 30.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  31. 31.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  32. 32.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  33. 33.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  34. 34.Which of these is a perfect cube? (a) 2909 (b) 2808 (c) 2744
  35. 35.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  37. 37.What is ∛729? =
  38. 38.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  39. 39.What is ∛12167? =
  40. 40.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?

Answer key

  1. 125
  2. 343
  3. 27
  4. 512
  5. 2
  6. 18
  7. 7
  8. 15
  9. 4913
  10. 2744
  11. 14
  12. 125
  13. 3
  14. 125
  15. 3
  16. 49
  17. 27
  18. 24
  19. 27
  20. 729
  21. 3
  22. 1331
  23. 1728
  24. 7
  25. 8
  26. 2
  27. 20
  28. 1000
  29. 5832
  30. 9
  31. 125
  32. 64
  33. 4
  34. 2744
  35. 64
  36. 15
  37. 9
  38. 2
  39. 23
  40. 216

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