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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 982 · 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 ∛27? =
  2. 2.Which of these is a perfect cube? (a) 1728 (b) 1904 (c) 1968
  3. 3.What is 3³? =
  4. 4.Which of these is a perfect cube? (a) 745 (b) 770 (c) 729
  5. 5.What is ∛6859? =
  6. 6.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  7. 7.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  8. 8.Which of these is a perfect cube? (a) 171 (b) 125 (c) 185
  9. 9.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  11. 11.What is 4³? =
  12. 12.What is ∛1331? =
  13. 13.What is 14³? =
  14. 14.What is 2³? =
  15. 15.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  16. 16.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  17. 17.What is 17³? =
  18. 18.What is 9³? =
  19. 19.What is 18³? =
  20. 20.What is 16³? =
  21. 21.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  22. 22.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  23. 23.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  24. 24.What is ∛2197? =
  25. 25.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  26. 26.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  27. 27.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.What is ∛729? =
  30. 30.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  31. 31.What is ∛4913? =
  32. 32.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  33. 33.Which of these is a perfect cube? (a) 64 (b) 97 (c) 85
  34. 34.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.What is ∛3375? =
  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.What is 11³? =
  38. 38.What is ∛5832? =
  39. 39.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  40. 40.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?

Answer key

  1. 3
  2. 1728
  3. 27
  4. 729
  5. 19
  6. 20
  7. 4
  8. 125
  9. 64
  10. 8
  11. 64
  12. 11
  13. 2744
  14. 8
  15. 7
  16. 5
  17. 4913
  18. 729
  19. 5832
  20. 4096
  21. 125
  22. 49
  23. 19
  24. 13
  25. 16
  26. 2
  27. 216
  28. 64
  29. 9
  30. 25
  31. 17
  32. 15
  33. 64
  34. 216
  35. 15
  36. 125
  37. 1331
  38. 18
  39. 27
  40. 8

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