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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 680 · 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 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is ∛27? =
  3. 3.What is 10³? =
  4. 4.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  5. 5.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  6. 6.What is 17³? =
  7. 7.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  8. 8.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  9. 9.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  10. 10.Which of these is a perfect cube? (a) 418 (b) 359 (c) 343
  11. 11.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  12. 12.Which of these is a perfect cube? (a) 67 (b) 64 (c) 106
  13. 13.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.What is ∛512? =
  15. 15.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  16. 16.What is 7³? =
  17. 17.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  18. 18.What is ∛729? =
  19. 19.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  21. 21.Which of these is a perfect cube? (a) 2744 (b) 2974 (c) 3264
  22. 22.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  23. 23.Which of these is a perfect cube? (a) 156 (b) 188 (c) 125
  24. 24.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  25. 25.What is 3³? =
  26. 26.What is ∛4096? =
  27. 27.What is 5³? =
  28. 28.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  30. 30.What is ∛12167? =
  31. 31.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  32. 32.What is 4³? =
  33. 33.What is ∛8? =
  34. 34.What is 6³? =
  35. 35.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  37. 37.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  38. 38.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  40. 40.What is ∛1728? =

Answer key

  1. 216
  2. 3
  3. 1000
  4. 125
  5. 17
  6. 4913
  7. 25
  8. 9
  9. 8
  10. 343
  11. 3
  12. 64
  13. 216
  14. 8
  15. 5
  16. 343
  17. 7
  18. 9
  19. 125
  20. 16
  21. 2744
  22. 13
  23. 125
  24. 3
  25. 27
  26. 16
  27. 125
  28. 125
  29. 5
  30. 23
  31. 5
  32. 64
  33. 2
  34. 216
  35. 64
  36. 4
  37. 25
  38. 216
  39. 2
  40. 12

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