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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 717 · 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 6³? =
  2. 2.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.What is 13³? =
  4. 4.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  5. 5.What is ∛1000? =
  6. 6.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  7. 7.What is ∛512? =
  8. 8.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  9. 9.Which of these is a perfect cube? (a) 216 (b) 321 (c) 291
  10. 10.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  11. 11.What is 7³? =
  12. 12.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  13. 13.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  14. 14.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  15. 15.What is ∛4913? =
  16. 16.What is ∛1728? =
  17. 17.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  18. 18.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  19. 19.What is ∛4096? =
  20. 20.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  22. 22.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  23. 23.What is 11³? =
  24. 24.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  25. 25.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  26. 26.What is 18³? =
  27. 27.What is ∛125? =
  28. 28.What is ∛10648? =
  29. 29.What is 3³? =
  30. 30.What is 8³? =
  31. 31.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  32. 32.What is 20³? =
  33. 33.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  36. 36.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  37. 37.What is ∛8000? =
  38. 38.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  39. 39.Which of these is a perfect cube? (a) 3967 (b) 3375 (c) 3624
  40. 40.What is the smallest whole number by which 56 must be divided to get a perfect cube?

Answer key

  1. 216
  2. 216
  3. 2197
  4. 27
  5. 10
  6. 6
  7. 8
  8. 17
  9. 216
  10. 11
  11. 343
  12. 5
  13. 27
  14. 9
  15. 17
  16. 12
  17. 2
  18. 7
  19. 16
  20. 18
  21. 216
  22. 4
  23. 1331
  24. 9
  25. 4
  26. 5832
  27. 5
  28. 22
  29. 27
  30. 512
  31. 15
  32. 8000
  33. 125
  34. 2
  35. 2
  36. 64
  37. 20
  38. 2
  39. 3375
  40. 7

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