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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 422 · 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 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.What is ∛9261? =
  3. 3.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  4. 4.What is ∛2744? =
  5. 5.Which of these is a perfect cube? (a) 133 (b) 125 (c) 192
  6. 6.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  7. 7.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  10. 10.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  11. 11.Which of these is a perfect cube? (a) 954 (b) 729 (c) 784
  12. 12.Which of these is a perfect cube? (a) 1000 (b) 1103 (c) 1071
  13. 13.What is ∛8? =
  14. 14.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  15. 15.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  17. 17.What is 15³? =
  18. 18.What is ∛3375? =
  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 the smallest whole number by which 250 must be multiplied to get a perfect cube?
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  22. 22.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  23. 23.Which of these is a perfect cube? (a) 314 (b) 216 (c) 220
  24. 24.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  25. 25.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  26. 26.Which of these is a perfect cube? (a) 27 (b) 42 (c) 43
  27. 27.What is ∛125? =
  28. 28.What is ∛1331? =
  29. 29.What is ∛216? =
  30. 30.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  32. 32.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  33. 33.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.What is 10³? =
  35. 35.What is 3³? =
  36. 36.What is 2³? =
  37. 37.What is 7³? =
  38. 38.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  39. 39.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  40. 40.What is 13³? =

Answer key

  1. 64
  2. 21
  3. 3
  4. 14
  5. 125
  6. 10
  7. 216
  8. 8
  9. 7
  10. 4
  11. 729
  12. 1000
  13. 2
  14. 27
  15. 8
  16. 8
  17. 3375
  18. 15
  19. 125
  20. 4
  21. 27
  22. 9
  23. 216
  24. 9
  25. 2
  26. 27
  27. 5
  28. 11
  29. 6
  30. 2
  31. 9
  32. 16
  33. 27
  34. 1000
  35. 27
  36. 8
  37. 343
  38. 3
  39. 12
  40. 2197

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