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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 752 · 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 189 must be divided to get a perfect cube?
  2. 2.What is ∛5832? =
  3. 3.What is 5³? =
  4. 4.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  5. 5.What is ∛15625? =
  6. 6.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  7. 7.What is ∛1000? =
  8. 8.What is ∛512? =
  9. 9.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  11. 11.Which of these is a perfect cube? (a) 486 (b) 381 (c) 343
  12. 12.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  13. 13.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  14. 14.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  15. 15.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 3296 (b) 2744 (c) 3171
  17. 17.What is 2³? =
  18. 18.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  19. 19.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  20. 20.What is 11³? =
  21. 21.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  23. 23.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  25. 25.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  26. 26.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.What is ∛343? =
  28. 28.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  29. 29.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  30. 30.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  32. 32.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  33. 33.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  34. 34.What is ∛729? =
  35. 35.What is 13³? =
  36. 36.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.Which of these is a perfect cube? (a) 125 (b) 130 (c) 133
  39. 39.What is ∛4096? =
  40. 40.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?

Answer key

  1. 7
  2. 18
  3. 125
  4. 49
  5. 25
  6. 12
  7. 10
  8. 8
  9. 125
  10. 6
  11. 343
  12. 216
  13. 7
  14. 4
  15. 216
  16. 2744
  17. 8
  18. 16
  19. 7
  20. 1331
  21. 27
  22. 5
  23. 125
  24. 17
  25. 3
  26. 27
  27. 7
  28. 3
  29. 25
  30. 5
  31. 2
  32. 2
  33. 8
  34. 9
  35. 2197
  36. 8
  37. 216
  38. 125
  39. 16
  40. 5

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