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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 242 · 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 20³? =
  2. 2.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.What is 3³? =
  4. 4.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.What is ∛12167? =
  7. 7.Which of these is a perfect cube? (a) 3548 (b) 3375 (c) 4036
  8. 8.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  9. 9.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.What is ∛1728? =
  11. 11.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  12. 12.Which of these is a perfect cube? (a) 729 (b) 771 (c) 879
  13. 13.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  14. 14.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  15. 15.What is 13³? =
  16. 16.What is ∛125? =
  17. 17.What is ∛9261? =
  18. 18.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  19. 19.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  20. 20.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  21. 21.What is 14³? =
  22. 22.What is 11³? =
  23. 23.What is ∛512? =
  24. 24.What is ∛2197? =
  25. 25.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  26. 26.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  27. 27.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  28. 28.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  30. 30.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  31. 31.What is 15³? =
  32. 32.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  33. 33.What is ∛4096? =
  34. 34.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  35. 35.What is ∛729? =
  36. 36.Which of these is a perfect cube? (a) 347 (b) 484 (c) 343
  37. 37.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  38. 38.Which of these is a perfect cube? (a) 64 (b) 106 (c) 88
  39. 39.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?

Answer key

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

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