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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 808 · 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 375 must be divided to get a perfect cube?
  2. 2.What is 11³? =
  3. 3.Which of these is a perfect cube? (a) 1000 (b) 1089 (c) 1275
  4. 4.What is ∛8? =
  5. 5.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  6. 6.What is 19³? =
  7. 7.Which of these is a perfect cube? (a) 343 (b) 369 (c) 351
  8. 8.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  10. 10.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  11. 11.What is 15³? =
  12. 12.Which of these is a perfect cube? (a) 2967 (b) 2744 (c) 2818
  13. 13.What is 2³? =
  14. 14.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  15. 15.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  16. 16.What is ∛3375? =
  17. 17.What is ∛1728? =
  18. 18.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  19. 19.Which of these is a perfect cube? (a) 1988 (b) 1843 (c) 1728
  20. 20.What is 5³? =
  21. 21.Which of these is a perfect cube? (a) 69 (b) 64 (c) 77
  22. 22.What is ∛8000? =
  23. 23.What is ∛10648? =
  24. 24.What is 12³? =
  25. 25.What is ∛4096? =
  26. 26.Which of these is a perfect cube? (a) 851 (b) 729 (c) 747
  27. 27.What is 4³? =
  28. 28.What is ∛216? =
  29. 29.What is ∛9261? =
  30. 30.What is ∛5832? =
  31. 31.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  32. 32.What is ∛4913? =
  33. 33.What is ∛2744? =
  34. 34.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  35. 35.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  36. 36.Which of these is a perfect cube? (a) 3375 (b) 3946 (c) 3568
  37. 37.What is ∛27? =
  38. 38.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 81 must be divided to get a perfect cube?

Answer key

  1. 3
  2. 1331
  3. 1000
  4. 2
  5. 9
  6. 6859
  7. 343
  8. 216
  9. 25
  10. 2
  11. 3375
  12. 2744
  13. 8
  14. 5
  15. 2
  16. 15
  17. 12
  18. 7
  19. 1728
  20. 125
  21. 64
  22. 20
  23. 22
  24. 1728
  25. 16
  26. 729
  27. 64
  28. 6
  29. 21
  30. 18
  31. 49
  32. 17
  33. 14
  34. 17
  35. 2
  36. 3375
  37. 3
  38. 8
  39. 11
  40. 3

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