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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 883 · 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 4³? =
  2. 2.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  3. 3.What is ∛4913? =
  4. 4.Which of these is a perfect cube? (a) 2197 (b) 2495 (c) 2481
  5. 5.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  6. 6.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  7. 7.What is 20³? =
  8. 8.Which of these is a perfect cube? (a) 181 (b) 125 (c) 171
  9. 9.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.What is ∛125? =
  11. 11.What is 6³? =
  12. 12.What is ∛8? =
  13. 13.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  14. 14.What is 14³? =
  15. 15.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  16. 16.What is 13³? =
  17. 17.What is ∛2197? =
  18. 18.What is 12³? =
  19. 19.What is 10³? =
  20. 20.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  21. 21.Which of these is a perfect cube? (a) 729 (b) 896 (c) 913
  22. 22.What is 15³? =
  23. 23.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  24. 24.What is 17³? =
  25. 25.What is ∛9261? =
  26. 26.What is ∛64? =
  27. 27.What is ∛729? =
  28. 28.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  30. 30.What is ∛3375? =
  31. 31.What is ∛13824? =
  32. 32.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  33. 33.What is 19³? =
  34. 34.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  35. 35.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  36. 36.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.What is ∛15625? =
  38. 38.Which of these is a perfect cube? (a) 551 (b) 512 (c) 653
  39. 39.What is ∛8000? =
  40. 40.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?

Answer key

  1. 64
  2. 25
  3. 17
  4. 2197
  5. 16
  6. 49
  7. 8000
  8. 125
  9. 27
  10. 5
  11. 216
  12. 2
  13. 64
  14. 2744
  15. 49
  16. 2197
  17. 13
  18. 1728
  19. 1000
  20. 20
  21. 729
  22. 3375
  23. 4
  24. 4913
  25. 21
  26. 4
  27. 9
  28. 125
  29. 7
  30. 15
  31. 24
  32. 7
  33. 6859
  34. 3
  35. 11
  36. 8
  37. 25
  38. 512
  39. 20
  40. 9

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