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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 111 · 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 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  4. 4.Which of these is a perfect cube? (a) 690 (b) 512 (c) 636
  5. 5.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  6. 6.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  7. 7.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  9. 9.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  10. 10.What is 5³? =
  11. 11.What is ∛10648? =
  12. 12.Which of these is a perfect cube? (a) 38 (b) 36 (c) 27
  13. 13.What is 8³? =
  14. 14.What is 17³? =
  15. 15.What is ∛8? =
  16. 16.What is ∛343? =
  17. 17.What is 10³? =
  18. 18.What is 6³? =
  19. 19.What is ∛13824? =
  20. 20.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  21. 21.What is ∛64? =
  22. 22.What is 12³? =
  23. 23.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  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.What is 18³? =
  28. 28.Which of these is a perfect cube? (a) 1534 (b) 1471 (c) 1331
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 468 (b) 480 (c) 343
  31. 31.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  32. 32.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  33. 33.What is ∛8000? =
  34. 34.What is 7³? =
  35. 35.Which of these is a perfect cube? (a) 265 (b) 216 (c) 233
  36. 36.What is ∛125? =
  37. 37.What is 13³? =
  38. 38.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  39. 39.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?

Answer key

  1. 64
  2. 125
  3. 125
  4. 512
  5. 2
  6. 2
  7. 27
  8. 7
  9. 5
  10. 125
  11. 22
  12. 27
  13. 512
  14. 4913
  15. 2
  16. 7
  17. 1000
  18. 216
  19. 24
  20. 6
  21. 4
  22. 1728
  23. 64
  24. 27
  25. 216
  26. 8
  27. 5832
  28. 1331
  29. 8
  30. 343
  31. 12
  32. 3
  33. 20
  34. 343
  35. 216
  36. 5
  37. 2197
  38. 49
  39. 25
  40. 15

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