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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 166 · 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 56 must be divided to get a perfect cube?
  2. 2.Which of these is a perfect cube? (a) 729 (b) 739 (c) 854
  3. 3.Which of these is a perfect cube? (a) 254 (b) 305 (c) 216
  4. 4.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  5. 5.What is ∛4913? =
  6. 6.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.Which of these is a perfect cube? (a) 1795 (b) 1728 (c) 1760
  8. 8.What is ∛10648? =
  9. 9.Which of these is a perfect cube? (a) 357 (b) 343 (c) 425
  10. 10.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  11. 11.What is ∛6859? =
  12. 12.What is ∛512? =
  13. 13.What is ∛1331? =
  14. 14.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  15. 15.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  16. 16.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  17. 17.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  18. 18.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  19. 19.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  20. 20.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  21. 21.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  22. 22.Which of these is a perfect cube? (a) 64 (b) 91 (c) 97
  23. 23.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  24. 24.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  25. 25.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  26. 26.What is ∛343? =
  27. 27.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  28. 28.Which of these is a perfect cube? (a) 1147 (b) 1000 (c) 1021
  29. 29.What is ∛3375? =
  30. 30.What is 5³? =
  31. 31.What is 20³? =
  32. 32.What is 3³? =
  33. 33.What is 12³? =
  34. 34.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 512 (b) 642 (c) 675
  36. 36.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  40. 40.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 7
  2. 729
  3. 216
  4. 2
  5. 17
  6. 64
  7. 1728
  8. 22
  9. 343
  10. 9
  11. 19
  12. 8
  13. 11
  14. 11
  15. 10
  16. 8
  17. 9
  18. 12
  19. 2
  20. 18
  21. 16
  22. 64
  23. 7
  24. 4
  25. 5
  26. 7
  27. 2
  28. 1000
  29. 15
  30. 125
  31. 8000
  32. 27
  33. 1728
  34. 25
  35. 512
  36. 17
  37. 2
  38. 49
  39. 3
  40. 125

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