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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 727 · 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 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.What is ∛8000? =
  3. 3.What is 2³? =
  4. 4.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  6. 6.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  7. 7.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  8. 8.Which of these is a perfect cube? (a) 287 (b) 231 (c) 216
  9. 9.What is ∛4913? =
  10. 10.What is 7³? =
  11. 11.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  12. 12.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  14. 14.Which of these is a perfect cube? (a) 193 (b) 143 (c) 125
  15. 15.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  16. 16.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  17. 17.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.Which of these is a perfect cube? (a) 475 (b) 343 (c) 483
  19. 19.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  20. 20.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  21. 21.Which of these is a perfect cube? (a) 64 (b) 90 (c) 98
  22. 22.What is ∛9261? =
  23. 23.What is 16³? =
  24. 24.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.What is ∛1728? =
  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 10³? =
  28. 28.What is ∛3375? =
  29. 29.What is ∛4096? =
  30. 30.What is ∛1000? =
  31. 31.What is 3³? =
  32. 32.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is ∛125? =
  34. 34.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 33 (b) 44 (c) 27
  36. 36.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  37. 37.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  38. 38.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  39. 39.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  40. 40.What is ∛13824? =

Answer key

  1. 8
  2. 20
  3. 8
  4. 27
  5. 5
  6. 5
  7. 7
  8. 216
  9. 17
  10. 343
  11. 7
  12. 15
  13. 17
  14. 125
  15. 2
  16. 8
  17. 27
  18. 343
  19. 7
  20. 2
  21. 64
  22. 21
  23. 4096
  24. 8
  25. 12
  26. 27
  27. 1000
  28. 15
  29. 16
  30. 10
  31. 27
  32. 216
  33. 5
  34. 3
  35. 27
  36. 2
  37. 4
  38. 19
  39. 7
  40. 24

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