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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 386 · 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 ∛27? =
  2. 2.What is ∛729? =
  3. 3.What is 15³? =
  4. 4.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  5. 5.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  6. 6.What is 19³? =
  7. 7.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  8. 8.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  9. 9.What is 18³? =
  10. 10.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  11. 11.What is ∛2197? =
  12. 12.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  13. 13.What is 6³? =
  14. 14.What is 7³? =
  15. 15.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  16. 16.What is 5³? =
  17. 17.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  18. 18.What is 10³? =
  19. 19.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  20. 20.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  21. 21.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is ∛64? =
  23. 23.Which of these is a perfect cube? (a) 1021 (b) 1000 (c) 1227
  24. 24.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.What is 20³? =
  26. 26.What is ∛125? =
  27. 27.What is 17³? =
  28. 28.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  29. 29.What is 3³? =
  30. 30.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  31. 31.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  32. 32.What is ∛6859? =
  33. 33.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  34. 34.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.Which of these is a perfect cube? (a) 107 (b) 68 (c) 64
  36. 36.What is 8³? =
  37. 37.What is ∛10648? =
  38. 38.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  39. 39.What is ∛216? =
  40. 40.What is ∛1000? =

Answer key

  1. 3
  2. 9
  3. 3375
  4. 64
  5. 25
  6. 6859
  7. 9
  8. 19
  9. 5832
  10. 9
  11. 13
  12. 2
  13. 216
  14. 343
  15. 12
  16. 125
  17. 49
  18. 1000
  19. 5
  20. 10
  21. 125
  22. 4
  23. 1000
  24. 27
  25. 8000
  26. 5
  27. 4913
  28. 4
  29. 27
  30. 8
  31. 49
  32. 19
  33. 6
  34. 8
  35. 64
  36. 512
  37. 22
  38. 25
  39. 6
  40. 10

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