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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 286 · 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 27 cubic cm. How long is each edge (in cm)?
  2. 2.What is 20³? =
  3. 3.What is ∛4096? =
  4. 4.What is ∛343? =
  5. 5.What is 14³? =
  6. 6.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  7. 7.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  8. 8.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  10. 10.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  11. 11.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  12. 12.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  13. 13.What is 15³? =
  14. 14.What is ∛2744? =
  15. 15.What is ∛8? =
  16. 16.Which of these is a perfect cube? (a) 835 (b) 814 (c) 729
  17. 17.Which of these is a perfect cube? (a) 263 (b) 216 (c) 242
  18. 18.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  19. 19.Which of these is a perfect cube? (a) 159 (b) 155 (c) 125
  20. 20.What is 11³? =
  21. 21.What is 3³? =
  22. 22.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  23. 23.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  24. 24.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  25. 25.What is ∛512? =
  26. 26.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  27. 27.What is ∛2197? =
  28. 28.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.What is ∛216? =
  31. 31.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  32. 32.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  33. 33.What is ∛64? =
  34. 34.Which of these is a perfect cube? (a) 1379 (b) 1331 (c) 1603
  35. 35.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.What is ∛3375? =
  37. 37.What is ∛5832? =
  38. 38.What is ∛9261? =
  39. 39.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 72 must be divided to get a perfect cube?

Answer key

  1. 3
  2. 8000
  3. 16
  4. 7
  5. 2744
  6. 16
  7. 2
  8. 8
  9. 5
  10. 10
  11. 7
  12. 25
  13. 3375
  14. 14
  15. 2
  16. 729
  17. 216
  18. 125
  19. 125
  20. 1331
  21. 27
  22. 49
  23. 8
  24. 9
  25. 8
  26. 4
  27. 13
  28. 27
  29. 216
  30. 6
  31. 216
  32. 5
  33. 4
  34. 1331
  35. 64
  36. 15
  37. 18
  38. 21
  39. 20
  40. 9

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