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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 742 · 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.Which of these is a perfect cube? (a) 305 (b) 216 (c) 225
  3. 3.What is 5³? =
  4. 4.Which of these is a perfect cube? (a) 1000 (b) 1078 (c) 1093
  5. 5.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  6. 6.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  7. 7.Which of these is a perfect cube? (a) 125 (b) 157 (c) 141
  8. 8.What is 12³? =
  9. 9.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  10. 10.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  11. 11.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  12. 12.Which of these is a perfect cube? (a) 741 (b) 729 (c) 824
  13. 13.A big cube of edge 12 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 9 must be divided to get a perfect cube?
  15. 15.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  16. 16.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  17. 17.What is ∛64? =
  18. 18.Which of these is a perfect cube? (a) 343 (b) 378 (c) 383
  19. 19.What is 2³? =
  20. 20.What is ∛13824? =
  21. 21.What is 11³? =
  22. 22.Which of these is a perfect cube? (a) 2204 (b) 2601 (c) 2197
  23. 23.What is ∛27? =
  24. 24.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  25. 25.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  26. 26.What is ∛2197? =
  27. 27.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  28. 28.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛216? =
  30. 30.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  31. 31.Which of these is a perfect cube? (a) 1395 (b) 1589 (c) 1331
  32. 32.What is ∛2744? =
  33. 33.What is ∛3375? =
  34. 34.What is ∛4913? =
  35. 35.Which of these is a perfect cube? (a) 2744 (b) 2876 (c) 2760
  36. 36.What is 14³? =
  37. 37.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  38. 38.What is 15³? =
  39. 39.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  40. 40.What is 20³? =

Answer key

  1. 216
  2. 216
  3. 125
  4. 1000
  5. 19
  6. 64
  7. 125
  8. 1728
  9. 2
  10. 4
  11. 5
  12. 729
  13. 216
  14. 9
  15. 2
  16. 18
  17. 4
  18. 343
  19. 8
  20. 24
  21. 1331
  22. 2197
  23. 3
  24. 7
  25. 64
  26. 13
  27. 8
  28. 9
  29. 6
  30. 5
  31. 1331
  32. 14
  33. 15
  34. 17
  35. 2744
  36. 2744
  37. 4
  38. 3375
  39. 27
  40. 8000

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