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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 260 · 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.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is 16³? =
  3. 3.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  5. 5.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  6. 6.What is 2³? =
  7. 7.Which of these is a perfect cube? (a) 353 (b) 356 (c) 343
  8. 8.What is 20³? =
  9. 9.What is ∛9261? =
  10. 10.What is ∛343? =
  11. 11.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  12. 12.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  13. 13.What is ∛2197? =
  14. 14.What is ∛13824? =
  15. 15.What is 19³? =
  16. 16.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  17. 17.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  18. 18.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  19. 19.What is 6³? =
  20. 20.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  21. 21.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  22. 22.What is ∛27? =
  23. 23.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 84 (b) 64 (c) 83
  25. 25.Which of these is a perfect cube? (a) 31 (b) 27 (c) 44
  26. 26.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  27. 27.Which of these is a perfect cube? (a) 1890 (b) 2065 (c) 1728
  28. 28.What is ∛5832? =
  29. 29.What is 3³? =
  30. 30.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  31. 31.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  32. 32.What is 15³? =
  33. 33.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  34. 34.What is 4³? =
  35. 35.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  37. 37.What is ∛216? =
  38. 38.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  39. 39.What is ∛6859? =
  40. 40.Which of these is a perfect cube? (a) 313 (b) 216 (c) 285

Answer key

  1. 27
  2. 4096
  3. 125
  4. 49
  5. 11
  6. 8
  7. 343
  8. 8000
  9. 21
  10. 7
  11. 7
  12. 4
  13. 13
  14. 24
  15. 6859
  16. 27
  17. 12
  18. 5
  19. 216
  20. 6
  21. 216
  22. 3
  23. 49
  24. 64
  25. 27
  26. 19
  27. 1728
  28. 18
  29. 27
  30. 64
  31. 64
  32. 3375
  33. 3
  34. 64
  35. 5
  36. 3
  37. 6
  38. 2
  39. 19
  40. 216

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