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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 2 · 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 128 must be divided to get a perfect cube?
  2. 2.What is 17³? =
  3. 3.Which of these is a perfect cube? (a) 35 (b) 51 (c) 27
  4. 4.Which of these is a perfect cube? (a) 216 (b) 237 (c) 271
  5. 5.Which of these is a perfect cube? (a) 1339 (b) 1331 (c) 1610
  6. 6.What is ∛5832? =
  7. 7.What is 18³? =
  8. 8.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  9. 9.What is 14³? =
  10. 10.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  11. 11.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  12. 12.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is 12³? =
  14. 14.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  15. 15.Which of these is a perfect cube? (a) 643 (b) 512 (c) 613
  16. 16.What is 13³? =
  17. 17.What is ∛125? =
  18. 18.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  19. 19.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  20. 20.What is ∛3375? =
  21. 21.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  22. 22.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  23. 23.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  24. 24.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  25. 25.What is ∛1728? =
  26. 26.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  27. 27.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  28. 28.Which of these is a perfect cube? (a) 439 (b) 343 (c) 417
  29. 29.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  30. 30.What is 3³? =
  31. 31.What is ∛64? =
  32. 32.What is ∛8? =
  33. 33.What is ∛512? =
  34. 34.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  35. 35.What is ∛4913? =
  36. 36.What is ∛343? =
  37. 37.What is ∛2744? =
  38. 38.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  39. 39.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  40. 40.Which of these is a perfect cube? (a) 2197 (b) 2339 (c) 2609

Answer key

  1. 2
  2. 4913
  3. 27
  4. 216
  5. 1331
  6. 18
  7. 5832
  8. 8
  9. 2744
  10. 25
  11. 8
  12. 216
  13. 1728
  14. 2
  15. 512
  16. 2197
  17. 5
  18. 25
  19. 9
  20. 15
  21. 4
  22. 4
  23. 13
  24. 18
  25. 12
  26. 8
  27. 6
  28. 343
  29. 19
  30. 27
  31. 4
  32. 2
  33. 8
  34. 7
  35. 17
  36. 7
  37. 14
  38. 12
  39. 125
  40. 2197

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