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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 12 · 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 192 must be multiplied to get a perfect cube?
  2. 2.What is 17³? =
  3. 3.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  4. 4.What is 6³? =
  5. 5.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  6. 6.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  7. 7.What is ∛10648? =
  8. 8.Which of these is a perfect cube? (a) 584 (b) 515 (c) 512
  9. 9.What is ∛8? =
  10. 10.What is 20³? =
  11. 11.What is ∛216? =
  12. 12.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  13. 13.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  14. 14.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  15. 15.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  16. 16.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  17. 17.What is 14³? =
  18. 18.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  20. 20.Which of these is a perfect cube? (a) 30 (b) 27 (c) 54
  21. 21.What is ∛27? =
  22. 22.What is 2³? =
  23. 23.What is ∛3375? =
  24. 24.What is 9³? =
  25. 25.Which of these is a perfect cube? (a) 754 (b) 729 (c) 745
  26. 26.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  27. 27.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  29. 29.What is ∛2197? =
  30. 30.What is ∛512? =
  31. 31.What is ∛2744? =
  32. 32.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  33. 33.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  34. 34.What is 4³? =
  35. 35.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  36. 36.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.What is 11³? =
  38. 38.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  39. 39.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  40. 40.What is ∛729? =

Answer key

  1. 9
  2. 4913
  3. 16
  4. 216
  5. 3
  6. 17
  7. 22
  8. 512
  9. 2
  10. 8000
  11. 6
  12. 18
  13. 8
  14. 25
  15. 5
  16. 27
  17. 2744
  18. 8
  19. 3
  20. 27
  21. 3
  22. 8
  23. 15
  24. 729
  25. 729
  26. 14
  27. 125
  28. 49
  29. 13
  30. 8
  31. 14
  32. 3
  33. 5
  34. 64
  35. 25
  36. 125
  37. 1331
  38. 4
  39. 10
  40. 9

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