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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 605 · 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 ∛2744? =
  2. 2.Which of these is a perfect cube? (a) 216 (b) 257 (c) 297
  3. 3.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  5. 5.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  6. 6.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  7. 7.Which of these is a perfect cube? (a) 2744 (b) 3296 (c) 3083
  8. 8.What is 12³? =
  9. 9.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is ∛125? =
  12. 12.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  14. 14.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  15. 15.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  16. 16.What is 4³? =
  17. 17.What is 20³? =
  18. 18.What is 16³? =
  19. 19.What is 8³? =
  20. 20.What is ∛5832? =
  21. 21.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  22. 22.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  23. 23.What is ∛729? =
  24. 24.What is ∛343? =
  25. 25.What is 14³? =
  26. 26.Which of these is a perfect cube? (a) 343 (b) 464 (c) 430
  27. 27.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  28. 28.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  31. 31.What is 15³? =
  32. 32.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  33. 33.What is ∛8? =
  34. 34.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  35. 35.Which of these is a perfect cube? (a) 28 (b) 40 (c) 27
  36. 36.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  37. 37.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  38. 38.Which of these is a perfect cube? (a) 567 (b) 581 (c) 512
  39. 39.What is ∛216? =
  40. 40.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?

Answer key

  1. 14
  2. 216
  3. 216
  4. 3
  5. 9
  6. 15
  7. 2744
  8. 1728
  9. 216
  10. 64
  11. 5
  12. 13
  13. 8
  14. 12
  15. 9
  16. 64
  17. 8000
  18. 4096
  19. 512
  20. 18
  21. 2
  22. 7
  23. 9
  24. 7
  25. 2744
  26. 343
  27. 17
  28. 216
  29. 64
  30. 7
  31. 3375
  32. 27
  33. 2
  34. 2
  35. 27
  36. 49
  37. 5
  38. 512
  39. 6
  40. 7

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