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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 406 · 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 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  2. 2.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  3. 3.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  4. 4.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  6. 6.Which of these is a perfect cube? (a) 1773 (b) 1728 (c) 2046
  7. 7.What is ∛27? =
  8. 8.Which of these is a perfect cube? (a) 1331 (b) 1590 (c) 1499
  9. 9.Which of these is a perfect cube? (a) 27 (b) 29 (c) 30
  10. 10.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  11. 11.What is ∛1331? =
  12. 12.What is ∛2197? =
  13. 13.What is 18³? =
  14. 14.What is 3³? =
  15. 15.What is ∛1728? =
  16. 16.What is ∛1000? =
  17. 17.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  18. 18.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  19. 19.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  20. 20.What is 6³? =
  21. 21.What is 16³? =
  22. 22.What is 10³? =
  23. 23.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  24. 24.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  25. 25.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  26. 26.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  27. 27.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  28. 28.What is 5³? =
  29. 29.Which of these is a perfect cube? (a) 92 (b) 108 (c) 64
  30. 30.What is 4³? =
  31. 31.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  32. 32.Which of these is a perfect cube? (a) 343 (b) 438 (c) 483
  33. 33.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  35. 35.What is 15³? =
  36. 36.What is 2³? =
  37. 37.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  38. 38.What is 19³? =
  39. 39.What is 17³? =
  40. 40.What is 14³? =

Answer key

  1. 125
  2. 9
  3. 6
  4. 64
  5. 17
  6. 1728
  7. 3
  8. 1331
  9. 27
  10. 7
  11. 11
  12. 13
  13. 5832
  14. 27
  15. 12
  16. 10
  17. 7
  18. 7
  19. 14
  20. 216
  21. 4096
  22. 1000
  23. 9
  24. 3
  25. 4
  26. 5
  27. 19
  28. 125
  29. 64
  30. 64
  31. 13
  32. 343
  33. 27
  34. 49
  35. 3375
  36. 8
  37. 25
  38. 6859
  39. 4913
  40. 2744

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