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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 868 · 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 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  3. 3.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  4. 4.Which of these is a perfect cube? (a) 2197 (b) 2474 (c) 2263
  5. 5.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  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 2197 cubic cm. How long is each edge (in cm)?
  8. 8.What is ∛13824? =
  9. 9.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  10. 10.Which of these is a perfect cube? (a) 3869 (b) 3375 (c) 3497
  11. 11.What is 5³? =
  12. 12.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  13. 13.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  14. 14.What is 4³? =
  15. 15.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  17. 17.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  18. 18.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  19. 19.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  20. 20.What is ∛27? =
  21. 21.Which of these is a perfect cube? (a) 163 (b) 125 (c) 196
  22. 22.What is 15³? =
  23. 23.What is ∛343? =
  24. 24.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  25. 25.What is ∛729? =
  26. 26.What is 13³? =
  27. 27.What is ∛1728? =
  28. 28.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  29. 29.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  30. 30.What is ∛9261? =
  31. 31.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  32. 32.What is ∛4096? =
  33. 33.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  34. 34.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 240 (b) 216 (c) 249
  36. 36.What is 16³? =
  37. 37.What is 7³? =
  38. 38.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  40. 40.What is ∛5832? =

Answer key

  1. 27
  2. 27
  3. 2
  4. 2197
  5. 15
  6. 20
  7. 13
  8. 24
  9. 9
  10. 3375
  11. 125
  12. 7
  13. 12
  14. 64
  15. 8
  16. 4
  17. 14
  18. 7
  19. 6
  20. 3
  21. 125
  22. 3375
  23. 7
  24. 5
  25. 9
  26. 2197
  27. 12
  28. 49
  29. 2
  30. 21
  31. 49
  32. 16
  33. 9
  34. 25
  35. 216
  36. 4096
  37. 343
  38. 27
  39. 216
  40. 18

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