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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 16 · 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 the smallest whole number by which 72 must be multiplied to get a perfect cube?
  2. 2.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  3. 3.What is ∛8? =
  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.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  6. 6.What is ∛10648? =
  7. 7.Which of these is a perfect cube? (a) 1837 (b) 1845 (c) 1728
  8. 8.What is 3³? =
  9. 9.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  11. 11.What is ∛216? =
  12. 12.Which of these is a perfect cube? (a) 2519 (b) 2197 (c) 2370
  13. 13.What is ∛12167? =
  14. 14.What is 6³? =
  15. 15.What is 7³? =
  16. 16.What is ∛5832? =
  17. 17.What is ∛8000? =
  18. 18.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  19. 19.What is ∛6859? =
  20. 20.Which of these is a perfect cube? (a) 1331 (b) 1619 (c) 1383
  21. 21.What is 4³? =
  22. 22.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  23. 23.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  24. 24.What is 8³? =
  25. 25.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  26. 26.What is ∛512? =
  27. 27.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  28. 28.What is 9³? =
  29. 29.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  30. 30.What is 18³? =
  31. 31.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  32. 32.What is ∛64? =
  33. 33.What is 15³? =
  34. 34.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  35. 35.What is ∛4913? =
  36. 36.Which of these is a perfect cube? (a) 3451 (b) 3553 (c) 3375
  37. 37.What is ∛125? =
  38. 38.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  39. 39.Which of these is a perfect cube? (a) 2744 (b) 3332 (c) 3085
  40. 40.What is the smallest whole number by which 1080 must be divided to get a perfect cube?

Answer key

  1. 3
  2. 16
  3. 2
  4. 64
  5. 5
  6. 22
  7. 1728
  8. 27
  9. 125
  10. 4
  11. 6
  12. 2197
  13. 23
  14. 216
  15. 343
  16. 18
  17. 20
  18. 8
  19. 19
  20. 1331
  21. 64
  22. 5
  23. 8
  24. 512
  25. 4
  26. 8
  27. 49
  28. 729
  29. 19
  30. 5832
  31. 7
  32. 4
  33. 3375
  34. 2
  35. 17
  36. 3375
  37. 5
  38. 9
  39. 2744
  40. 5

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