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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 827 · 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 the smallest whole number by which 1080 must be divided to get a perfect cube?
  2. 2.What is 17³? =
  3. 3.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  4. 4.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  5. 5.What is 4³? =
  6. 6.Which of these is a perfect cube? (a) 525 (b) 667 (c) 512
  7. 7.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  8. 8.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  9. 9.What is ∛9261? =
  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 243 must be multiplied to get a perfect cube?
  12. 12.What is ∛343? =
  13. 13.What is 6³? =
  14. 14.What is ∛1728? =
  15. 15.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  16. 16.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  17. 17.Which of these is a perfect cube? (a) 1000 (b) 1002 (c) 1177
  18. 18.What is 15³? =
  19. 19.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  20. 20.What is ∛10648? =
  21. 21.What is ∛1331? =
  22. 22.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  23. 23.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  24. 24.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  25. 25.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  26. 26.What is 5³? =
  27. 27.Which of these is a perfect cube? (a) 108 (b) 64 (c) 75
  28. 28.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.What is 14³? =
  30. 30.Which of these is a perfect cube? (a) 1658 (b) 1331 (c) 1459
  31. 31.What is ∛729? =
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  33. 33.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  34. 34.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  35. 35.What is 18³? =
  36. 36.What is 2³? =
  37. 37.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  40. 40.What is the smallest whole number by which 256 must be divided to get a perfect cube?

Answer key

  1. 5
  2. 4913
  3. 3
  4. 2
  5. 64
  6. 512
  7. 4
  8. 10
  9. 21
  10. 7
  11. 3
  12. 7
  13. 216
  14. 12
  15. 25
  16. 20
  17. 1000
  18. 3375
  19. 125
  20. 22
  21. 11
  22. 3
  23. 5
  24. 14
  25. 7
  26. 125
  27. 64
  28. 27
  29. 2744
  30. 1331
  31. 9
  32. 216
  33. 7
  34. 9
  35. 5832
  36. 8
  37. 8
  38. 64
  39. 5
  40. 4

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