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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 223 · 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 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.What is 15³? =
  3. 3.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  4. 4.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  5. 5.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  7. 7.What is 14³? =
  8. 8.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  9. 9.What is 9³? =
  10. 10.What is 10³? =
  11. 11.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  12. 12.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  13. 13.What is 2³? =
  14. 14.What is 7³? =
  15. 15.Which of these is a perfect cube? (a) 1000 (b) 1297 (c) 1242
  16. 16.What is 19³? =
  17. 17.Which of these is a perfect cube? (a) 52 (b) 27 (c) 28
  18. 18.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  19. 19.What is ∛343? =
  20. 20.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  21. 21.What is 5³? =
  22. 22.What is ∛9261? =
  23. 23.What is 20³? =
  24. 24.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  26. 26.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  27. 27.What is ∛10648? =
  28. 28.Which of these is a perfect cube? (a) 484 (b) 343 (c) 460
  29. 29.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  30. 30.Which of these is a perfect cube? (a) 2744 (b) 2748 (c) 3284
  31. 31.What is ∛13824? =
  32. 32.What is ∛6859? =
  33. 33.Which of these is a perfect cube? (a) 735 (b) 729 (c) 899
  34. 34.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  35. 35.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.What is ∛729? =
  37. 37.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  38. 38.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.What is ∛1728? =
  40. 40.Which of these is a perfect cube? (a) 3375 (b) 3388 (c) 3641

Answer key

  1. 64
  2. 3375
  3. 49
  4. 27
  5. 216
  6. 49
  7. 2744
  8. 12
  9. 729
  10. 1000
  11. 4
  12. 216
  13. 8
  14. 343
  15. 1000
  16. 6859
  17. 27
  18. 25
  19. 7
  20. 2
  21. 125
  22. 21
  23. 8000
  24. 64
  25. 27
  26. 8
  27. 22
  28. 343
  29. 14
  30. 2744
  31. 24
  32. 19
  33. 729
  34. 8
  35. 125
  36. 9
  37. 49
  38. 8
  39. 12
  40. 3375

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