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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 693 · 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 15³? =
  2. 2.What is 5³? =
  3. 3.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  4. 4.What is ∛6859? =
  5. 5.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  6. 6.What is 18³? =
  7. 7.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.What is 13³? =
  9. 9.What is 14³? =
  10. 10.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  11. 11.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  12. 12.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  13. 13.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  14. 14.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  15. 15.What is 9³? =
  16. 16.What is ∛1000? =
  17. 17.Which of these is a perfect cube? (a) 83 (b) 71 (c) 64
  18. 18.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  19. 19.What is ∛125? =
  20. 20.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  21. 21.What is 17³? =
  22. 22.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  23. 23.What is 3³? =
  24. 24.What is 11³? =
  25. 25.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  26. 26.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  27. 27.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.What is 20³? =
  29. 29.What is ∛27? =
  30. 30.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  31. 31.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  32. 32.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  33. 33.Which of these is a perfect cube? (a) 3375 (b) 3415 (c) 3771
  34. 34.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  35. 35.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  36. 36.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  37. 37.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  38. 38.What is ∛4096? =
  39. 39.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  40. 40.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 3375
  2. 125
  3. 4
  4. 19
  5. 2
  6. 5832
  7. 8
  8. 2197
  9. 2744
  10. 7
  11. 4
  12. 4
  13. 9
  14. 64
  15. 729
  16. 10
  17. 64
  18. 8
  19. 5
  20. 3
  21. 4913
  22. 8
  23. 27
  24. 1331
  25. 8
  26. 3
  27. 64
  28. 8000
  29. 3
  30. 3
  31. 2
  32. 2
  33. 3375
  34. 2
  35. 49
  36. 125
  37. 15
  38. 16
  39. 2
  40. 125

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