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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 102 · 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.What is ∛12167? =
  2. 2.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  4. 4.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  5. 5.What is 7³? =
  6. 6.What is 10³? =
  7. 7.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  8. 8.What is 3³? =
  9. 9.What is 20³? =
  10. 10.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  11. 11.What is ∛5832? =
  12. 12.What is 15³? =
  13. 13.What is ∛3375? =
  14. 14.What is ∛2197? =
  15. 15.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  16. 16.Which of these is a perfect cube? (a) 1590 (b) 1614 (c) 1331
  17. 17.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  18. 18.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  19. 19.Which of these is a perfect cube? (a) 3854 (b) 3375 (c) 3491
  20. 20.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  21. 21.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  22. 22.Which of these is a perfect cube? (a) 1784 (b) 2150 (c) 1728
  23. 23.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  24. 24.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  25. 25.Which of these is a perfect cube? (a) 64 (b) 101 (c) 111
  26. 26.Which of these is a perfect cube? (a) 2430 (b) 2417 (c) 2197
  27. 27.What is 13³? =
  28. 28.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is ∛1000? =
  30. 30.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  31. 31.What is ∛4913? =
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is 6³? =
  34. 34.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  36. 36.What is 4³? =
  37. 37.What is ∛343? =
  38. 38.Which of these is a perfect cube? (a) 512 (b) 544 (c) 531
  39. 39.What is 17³? =
  40. 40.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?

Answer key

  1. 23
  2. 8
  3. 125
  4. 15
  5. 343
  6. 1000
  7. 9
  8. 27
  9. 8000
  10. 7
  11. 18
  12. 3375
  13. 15
  14. 13
  15. 10
  16. 1331
  17. 9
  18. 13
  19. 3375
  20. 216
  21. 27
  22. 1728
  23. 17
  24. 12
  25. 64
  26. 2197
  27. 2197
  28. 64
  29. 10
  30. 14
  31. 17
  32. 8
  33. 216
  34. 7
  35. 7
  36. 64
  37. 7
  38. 512
  39. 4913
  40. 49

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