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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 790 · 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 343 cubic cm. How long is each edge (in cm)?
  2. 2.What is 14³? =
  3. 3.What is 6³? =
  4. 4.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  5. 5.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.What is 4³? =
  7. 7.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  8. 8.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  9. 9.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.What is ∛5832? =
  11. 11.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  12. 12.What is 3³? =
  13. 13.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  14. 14.What is 8³? =
  15. 15.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  16. 16.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  17. 17.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  18. 18.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  20. 20.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  21. 21.Which of these is a perfect cube? (a) 38 (b) 45 (c) 27
  22. 22.What is 18³? =
  23. 23.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  24. 24.What is 17³? =
  25. 25.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  26. 26.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  27. 27.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  28. 28.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.What is 15³? =
  31. 31.What is ∛729? =
  32. 32.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  33. 33.What is 10³? =
  34. 34.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  35. 35.What is ∛64? =
  36. 36.Which of these is a perfect cube? (a) 284 (b) 269 (c) 216
  37. 37.What is ∛6859? =
  38. 38.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  39. 39.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?

Answer key

  1. 7
  2. 2744
  3. 216
  4. 20
  5. 216
  6. 64
  7. 4
  8. 25
  9. 8
  10. 18
  11. 49
  12. 27
  13. 49
  14. 512
  15. 3
  16. 49
  17. 4
  18. 8
  19. 25
  20. 4
  21. 27
  22. 5832
  23. 9
  24. 4913
  25. 10
  26. 64
  27. 25
  28. 216
  29. 27
  30. 3375
  31. 9
  32. 3
  33. 1000
  34. 12
  35. 4
  36. 216
  37. 19
  38. 19
  39. 4
  40. 15

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