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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 308 · 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.Which of these is a perfect cube? (a) 512 (b) 577 (c) 633
  2. 2.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  3. 3.Which of these is a perfect cube? (a) 75 (b) 64 (c) 74
  4. 4.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  5. 5.What is ∛3375? =
  6. 6.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.What is ∛64? =
  8. 8.What is 5³? =
  9. 9.What is ∛13824? =
  10. 10.What is ∛10648? =
  11. 11.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  13. 13.What is 17³? =
  14. 14.What is ∛9261? =
  15. 15.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  16. 16.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  17. 17.What is ∛8000? =
  18. 18.What is ∛1000? =
  19. 19.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  20. 20.What is 11³? =
  21. 21.What is 16³? =
  22. 22.What is 18³? =
  23. 23.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  24. 24.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  25. 25.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  26. 26.Which of these is a perfect cube? (a) 351 (b) 346 (c) 343
  27. 27.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  28. 28.What is ∛12167? =
  29. 29.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  30. 30.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  31. 31.What is 4³? =
  32. 32.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  33. 33.What is 20³? =
  34. 34.Which of these is a perfect cube? (a) 3804 (b) 3375 (c) 4040
  35. 35.What is 6³? =
  36. 36.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is 9³? =
  38. 38.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.What is ∛343? =
  40. 40.Which of these is a perfect cube? (a) 1356 (b) 1517 (c) 1331

Answer key

  1. 512
  2. 9
  3. 64
  4. 4
  5. 15
  6. 125
  7. 4
  8. 125
  9. 24
  10. 22
  11. 64
  12. 64
  13. 4913
  14. 21
  15. 9
  16. 5
  17. 20
  18. 10
  19. 5
  20. 1331
  21. 4096
  22. 5832
  23. 8
  24. 27
  25. 27
  26. 343
  27. 7
  28. 23
  29. 4
  30. 216
  31. 64
  32. 4
  33. 8000
  34. 3375
  35. 216
  36. 125
  37. 729
  38. 125
  39. 7
  40. 1331

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