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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 575 · 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 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.What is 14³? =
  3. 3.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is 15³? =
  5. 5.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  6. 6.Which of these is a perfect cube? (a) 3255 (b) 2894 (c) 2744
  7. 7.What is 4³? =
  8. 8.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  9. 9.What is ∛2197? =
  10. 10.What is 19³? =
  11. 11.What is 10³? =
  12. 12.What is ∛1000? =
  13. 13.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  14. 14.What is ∛9261? =
  15. 15.What is ∛10648? =
  16. 16.What is ∛13824? =
  17. 17.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  18. 18.What is 13³? =
  19. 19.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  20. 20.What is 11³? =
  21. 21.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  22. 22.What is 17³? =
  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 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  25. 25.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 585 (b) 512 (c) 611
  27. 27.Which of these is a perfect cube? (a) 216 (b) 266 (c) 305
  28. 28.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.What is 16³? =
  31. 31.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  32. 32.Which of these is a perfect cube? (a) 27 (b) 34 (c) 31
  33. 33.What is ∛1728? =
  34. 34.What is ∛4913? =
  35. 35.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  36. 36.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  37. 37.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  38. 38.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  39. 39.Which of these is a perfect cube? (a) 144 (b) 125 (c) 137
  40. 40.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?

Answer key

  1. 27
  2. 2744
  3. 125
  4. 3375
  5. 2
  6. 2744
  7. 64
  8. 6
  9. 13
  10. 6859
  11. 1000
  12. 10
  13. 9
  14. 21
  15. 22
  16. 24
  17. 4
  18. 2197
  19. 7
  20. 1331
  21. 25
  22. 4913
  23. 8
  24. 8
  25. 7
  26. 512
  27. 216
  28. 49
  29. 27
  30. 4096
  31. 4
  32. 27
  33. 12
  34. 17
  35. 2
  36. 7
  37. 4
  38. 27
  39. 125
  40. 4

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