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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 811 · 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 2 must be divided to get a perfect cube?
  2. 2.What is 5³? =
  3. 3.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is 15³? =
  5. 5.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  6. 6.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  7. 7.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.What is ∛64? =
  10. 10.What is ∛8? =
  11. 11.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  12. 12.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  13. 13.What is ∛4913? =
  14. 14.What is ∛3375? =
  15. 15.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 46 (b) 42 (c) 27
  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) 539 (b) 602 (c) 512
  19. 19.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  20. 20.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  21. 21.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  22. 22.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  23. 23.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  24. 24.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  25. 25.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  26. 26.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  27. 27.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  29. 29.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 2744 (b) 3009 (c) 2797
  31. 31.What is 18³? =
  32. 32.Which of these is a perfect cube? (a) 319 (b) 216 (c) 246
  33. 33.What is ∛216? =
  34. 34.What is ∛1331? =
  35. 35.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  36. 36.Which of these is a perfect cube? (a) 198 (b) 125 (c) 188
  37. 37.What is 14³? =
  38. 38.What is 17³? =
  39. 39.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  40. 40.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?

Answer key

  1. 2
  2. 125
  3. 216
  4. 3375
  5. 2
  6. 11
  7. 27
  8. 27
  9. 4
  10. 2
  11. 25
  12. 16
  13. 17
  14. 15
  15. 7
  16. 27
  17. 27
  18. 512
  19. 4
  20. 8
  21. 5
  22. 4
  23. 4
  24. 49
  25. 3
  26. 3
  27. 64
  28. 49
  29. 216
  30. 2744
  31. 5832
  32. 216
  33. 6
  34. 11
  35. 2
  36. 125
  37. 2744
  38. 4913
  39. 25
  40. 125

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