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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 272 · 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 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.What is 10³? =
  3. 3.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  4. 4.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  5. 5.What is 12³? =
  6. 6.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  7. 7.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  8. 8.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  9. 9.What is ∛1728? =
  10. 10.What is ∛10648? =
  11. 11.What is ∛125? =
  12. 12.Which of these is a perfect cube? (a) 935 (b) 729 (c) 845
  13. 13.Which of these is a perfect cube? (a) 160 (b) 151 (c) 125
  14. 14.What is ∛13824? =
  15. 15.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  16. 16.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  17. 17.What is ∛9261? =
  18. 18.What is 4³? =
  19. 19.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  20. 20.What is 20³? =
  21. 21.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛729? =
  23. 23.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  24. 24.What is ∛15625? =
  25. 25.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  26. 26.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  27. 27.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  28. 28.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  29. 29.What is ∛27? =
  30. 30.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  31. 31.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  32. 32.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  33. 33.What is 18³? =
  34. 34.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  36. 36.What is 9³? =
  37. 37.What is ∛64? =
  38. 38.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  39. 39.Which of these is a perfect cube? (a) 86 (b) 64 (c) 87
  40. 40.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?

Answer key

  1. 216
  2. 1000
  3. 4
  4. 9
  5. 1728
  6. 6
  7. 3
  8. 5
  9. 12
  10. 22
  11. 5
  12. 729
  13. 125
  14. 24
  15. 64
  16. 2
  17. 21
  18. 64
  19. 49
  20. 8000
  21. 16
  22. 9
  23. 49
  24. 25
  25. 49
  26. 4
  27. 9
  28. 7
  29. 3
  30. 4
  31. 10
  32. 3
  33. 5832
  34. 4
  35. 2
  36. 729
  37. 4
  38. 17
  39. 64
  40. 8

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