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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 85 · 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 9³? =
  2. 2.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  3. 3.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  4. 4.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  5. 5.What is ∛2744? =
  6. 6.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  7. 7.Which of these is a perfect cube? (a) 729 (b) 764 (c) 936
  8. 8.Which of these is a perfect cube? (a) 1260 (b) 1208 (c) 1000
  9. 9.What is ∛27? =
  10. 10.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  11. 11.What is 3³? =
  12. 12.What is ∛4096? =
  13. 13.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  15. 15.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.What is 18³? =
  17. 17.What is 7³? =
  18. 18.Which of these is a perfect cube? (a) 2894 (b) 2744 (c) 3059
  19. 19.What is ∛4913? =
  20. 20.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  21. 21.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  22. 22.What is 11³? =
  23. 23.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  24. 24.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  25. 25.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  26. 26.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  27. 27.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  28. 28.A big cube of edge 10 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) 3406 (b) 3535 (c) 3375
  30. 30.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is ∛1728? =
  32. 32.Which of these is a perfect cube? (a) 69 (b) 64 (c) 96
  33. 33.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  34. 34.What is ∛1000? =
  35. 35.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.What is 8³? =
  37. 37.What is 15³? =
  38. 38.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  40. 40.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 729
  2. 17
  3. 9
  4. 216
  5. 14
  6. 4
  7. 729
  8. 1000
  9. 3
  10. 8
  11. 27
  12. 16
  13. 8
  14. 25
  15. 27
  16. 5832
  17. 343
  18. 2744
  19. 17
  20. 3
  21. 2
  22. 1331
  23. 64
  24. 7
  25. 3
  26. 12
  27. 9
  28. 125
  29. 3375
  30. 27
  31. 12
  32. 64
  33. 13
  34. 10
  35. 216
  36. 512
  37. 3375
  38. 64
  39. 49
  40. 216

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