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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 70 · 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.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  3. 3.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  4. 4.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  5. 5.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  6. 6.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  7. 7.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.Which of these is a perfect cube? (a) 3951 (b) 3375 (c) 3467
  9. 9.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.What is ∛512? =
  11. 11.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  12. 12.What is ∛729? =
  13. 13.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  16. 16.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  17. 17.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  19. 19.What is 2³? =
  20. 20.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  21. 21.Which of these is a perfect cube? (a) 479 (b) 472 (c) 343
  22. 22.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  23. 23.What is 12³? =
  24. 24.What is 16³? =
  25. 25.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  26. 26.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  27. 27.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  30. 30.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  31. 31.Which of these is a perfect cube? (a) 224 (b) 216 (c) 323
  32. 32.What is 6³? =
  33. 33.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  34. 34.What is ∛8? =
  35. 35.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.What is 14³? =
  37. 37.What is 4³? =
  38. 38.What is 20³? =
  39. 39.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  40. 40.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?

Answer key

  1. 14
  2. 8
  3. 4
  4. 64
  5. 3
  6. 8
  7. 125
  8. 3375
  9. 216
  10. 8
  11. 9
  12. 9
  13. 125
  14. 216
  15. 3
  16. 11
  17. 125
  18. 49
  19. 8
  20. 19
  21. 343
  22. 4
  23. 1728
  24. 4096
  25. 3
  26. 5
  27. 216
  28. 8
  29. 49
  30. 18
  31. 216
  32. 216
  33. 25
  34. 2
  35. 27
  36. 2744
  37. 64
  38. 8000
  39. 8
  40. 7

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