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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 119 · 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.Which of these is a perfect cube? (a) 251 (b) 216 (c) 218
  2. 2.What is ∛8? =
  3. 3.Which of these is a perfect cube? (a) 27 (b) 46 (c) 34
  4. 4.What is 5³? =
  5. 5.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  6. 6.What is 6³? =
  7. 7.Which of these is a perfect cube? (a) 663 (b) 691 (c) 512
  8. 8.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  9. 9.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  10. 10.Which of these is a perfect cube? (a) 414 (b) 343 (c) 386
  11. 11.What is 4³? =
  12. 12.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  13. 13.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  14. 14.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  15. 15.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  16. 16.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  17. 17.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  18. 18.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  19. 19.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  20. 20.What is 13³? =
  21. 21.What is ∛15625? =
  22. 22.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  23. 23.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  24. 24.What is 16³? =
  25. 25.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  26. 26.What is ∛4913? =
  27. 27.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  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 250 must be multiplied to get a perfect cube?
  30. 30.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  31. 31.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  32. 32.Which of these is a perfect cube? (a) 1408 (b) 1331 (c) 1497
  33. 33.What is ∛8000? =
  34. 34.What is ∛1331? =
  35. 35.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  36. 36.What is ∛125? =
  37. 37.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  38. 38.What is ∛9261? =
  39. 39.What is 9³? =
  40. 40.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 216
  2. 2
  3. 27
  4. 125
  5. 64
  6. 216
  7. 512
  8. 64
  9. 17
  10. 343
  11. 64
  12. 8
  13. 4
  14. 16
  15. 9
  16. 15
  17. 12
  18. 5
  19. 19
  20. 2197
  21. 25
  22. 9
  23. 8
  24. 4096
  25. 25
  26. 17
  27. 4
  28. 8
  29. 4
  30. 27
  31. 18
  32. 1331
  33. 20
  34. 11
  35. 9
  36. 5
  37. 5
  38. 21
  39. 729
  40. 64

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