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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 224 · 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 cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  2. 2.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  3. 3.What is ∛8? =
  4. 4.What is 19³? =
  5. 5.What is 17³? =
  6. 6.What is ∛64? =
  7. 7.What is 4³? =
  8. 8.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.Which of these is a perfect cube? (a) 1038 (b) 1031 (c) 1000
  10. 10.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  11. 11.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.Which of these is a perfect cube? (a) 125 (b) 156 (c) 145
  13. 13.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  14. 14.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  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 the smallest whole number by which 40 must be divided to get a perfect cube?
  17. 17.What is ∛6859? =
  18. 18.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  19. 19.What is 9³? =
  20. 20.What is ∛3375? =
  21. 21.What is 12³? =
  22. 22.What is the smallest whole number by which 3125 must be multiplied 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.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  26. 26.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  27. 27.Which of these is a perfect cube? (a) 3440 (b) 3375 (c) 3947
  28. 28.What is ∛1000? =
  29. 29.What is 14³? =
  30. 30.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  31. 31.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  32. 32.Which of these is a perfect cube? (a) 2744 (b) 2766 (c) 2970
  33. 33.What is 10³? =
  34. 34.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  37. 37.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  39. 39.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  40. 40.What is ∛216? =

Answer key

  1. 9
  2. 7
  3. 2
  4. 6859
  5. 4913
  6. 4
  7. 64
  8. 8
  9. 1000
  10. 5
  11. 125
  12. 125
  13. 4
  14. 125
  15. 27
  16. 5
  17. 19
  18. 216
  19. 729
  20. 15
  21. 1728
  22. 5
  23. 6
  24. 8
  25. 11
  26. 2
  27. 3375
  28. 10
  29. 2744
  30. 18
  31. 3
  32. 2744
  33. 1000
  34. 64
  35. 27
  36. 4
  37. 12
  38. 2
  39. 4
  40. 6

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