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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 714 · 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 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  3. 3.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  4. 4.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  5. 5.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  6. 6.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  7. 7.What is ∛8? =
  8. 8.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  9. 9.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  10. 10.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  11. 11.What is 12³? =
  12. 12.What is ∛2744? =
  13. 13.What is ∛512? =
  14. 14.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  15. 15.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.What is ∛1000? =
  17. 17.Which of these is a perfect cube? (a) 1814 (b) 2083 (c) 1728
  18. 18.Which of these is a perfect cube? (a) 97 (b) 103 (c) 64
  19. 19.What is 6³? =
  20. 20.What is 17³? =
  21. 21.What is 20³? =
  22. 22.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  23. 23.What is 19³? =
  24. 24.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  25. 25.What is ∛8000? =
  26. 26.What is 14³? =
  27. 27.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  28. 28.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  29. 29.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  30. 30.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  31. 31.Which of these is a perfect cube? (a) 298 (b) 216 (c) 217
  32. 32.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.What is ∛4096? =
  34. 34.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  35. 35.What is ∛64? =
  36. 36.What is ∛6859? =
  37. 37.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.What is ∛12167? =
  39. 39.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?

Answer key

  1. 216
  2. 7
  3. 17
  4. 3
  5. 3
  6. 8
  7. 2
  8. 49
  9. 9
  10. 2
  11. 1728
  12. 14
  13. 8
  14. 2
  15. 216
  16. 10
  17. 1728
  18. 64
  19. 216
  20. 4913
  21. 8000
  22. 64
  23. 6859
  24. 5
  25. 20
  26. 2744
  27. 3
  28. 4
  29. 2
  30. 4
  31. 216
  32. 125
  33. 16
  34. 8
  35. 4
  36. 19
  37. 125
  38. 23
  39. 25
  40. 11

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