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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 975 · 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.Which of these is a perfect cube? (a) 1791 (b) 1728 (c) 2089
  2. 2.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  3. 3.What is 10³? =
  4. 4.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  5. 5.What is 4³? =
  6. 6.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  8. 8.What is ∛125? =
  9. 9.What is 17³? =
  10. 10.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  11. 11.What is ∛4096? =
  12. 12.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  13. 13.What is 5³? =
  14. 14.What is 9³? =
  15. 15.Which of these is a perfect cube? (a) 31 (b) 27 (c) 49
  16. 16.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  17. 17.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  18. 18.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  19. 19.What is 13³? =
  20. 20.What is ∛13824? =
  21. 21.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  22. 22.What is 7³? =
  23. 23.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  24. 24.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  26. 26.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  27. 27.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  30. 30.What is ∛15625? =
  31. 31.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  32. 32.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  33. 33.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  34. 34.What is ∛2744? =
  35. 35.What is ∛343? =
  36. 36.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  37. 37.Which of these is a perfect cube? (a) 289 (b) 216 (c) 244
  38. 38.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  39. 39.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  40. 40.What is ∛512? =

Answer key

  1. 1728
  2. 4
  3. 1000
  4. 7
  5. 64
  6. 125
  7. 17
  8. 5
  9. 4913
  10. 2
  11. 16
  12. 49
  13. 125
  14. 729
  15. 27
  16. 10
  17. 3
  18. 9
  19. 2197
  20. 24
  21. 7
  22. 343
  23. 216
  24. 125
  25. 27
  26. 9
  27. 9
  28. 27
  29. 2
  30. 25
  31. 16
  32. 64
  33. 216
  34. 14
  35. 7
  36. 4
  37. 216
  38. 2
  39. 7
  40. 8

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