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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 661 · 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.Which of these is a perfect cube? (a) 1895 (b) 2144 (c) 1728
  2. 2.Which of these is a perfect cube? (a) 165 (b) 125 (c) 197
  3. 3.What is 7³? =
  4. 4.What is 13³? =
  5. 5.Which of these is a perfect cube? (a) 343 (b) 456 (c) 444
  6. 6.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  7. 7.What is ∛3375? =
  8. 8.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  10. 10.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is 18³? =
  12. 12.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  13. 13.Which of these is a perfect cube? (a) 2887 (b) 2744 (c) 2920
  14. 14.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  15. 15.What is 17³? =
  16. 16.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  17. 17.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  18. 18.What is 20³? =
  19. 19.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  20. 20.What is ∛10648? =
  21. 21.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  22. 22.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  23. 23.What is ∛12167? =
  24. 24.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  25. 25.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  26. 26.What is 2³? =
  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.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  30. 30.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  31. 31.What is 10³? =
  32. 32.Which of these is a perfect cube? (a) 781 (b) 729 (c) 753
  33. 33.What is ∛9261? =
  34. 34.Which of these is a perfect cube? (a) 1295 (b) 1200 (c) 1000
  35. 35.Which of these is a perfect cube? (a) 538 (b) 690 (c) 512
  36. 36.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  37. 37.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  38. 38.What is ∛64? =
  39. 39.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?

Answer key

  1. 1728
  2. 125
  3. 343
  4. 2197
  5. 343
  6. 3
  7. 15
  8. 27
  9. 25
  10. 125
  11. 5832
  12. 11
  13. 2744
  14. 4
  15. 4913
  16. 14
  17. 6
  18. 8000
  19. 18
  20. 22
  21. 5
  22. 3
  23. 23
  24. 5
  25. 2
  26. 8
  27. 64
  28. 216
  29. 4
  30. 9
  31. 1000
  32. 729
  33. 21
  34. 1000
  35. 512
  36. 27
  37. 20
  38. 4
  39. 5
  40. 25

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