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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 412 · 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 5 must be multiplied to get a perfect cube?
  2. 2.What is 9³? =
  3. 3.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  4. 4.Which of these is a perfect cube? (a) 729 (b) 972 (c) 737
  5. 5.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  8. 8.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.What is ∛343? =
  10. 10.What is 8³? =
  11. 11.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  12. 12.What is 6³? =
  13. 13.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  14. 14.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  15. 15.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  16. 16.What is ∛1728? =
  17. 17.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  18. 18.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  19. 19.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is 17³? =
  21. 21.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  22. 22.Which of these is a perfect cube? (a) 3375 (b) 3509 (c) 3798
  23. 23.What is ∛5832? =
  24. 24.What is ∛6859? =
  25. 25.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  26. 26.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  27. 27.Which of these is a perfect cube? (a) 33 (b) 27 (c) 36
  28. 28.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 125 (b) 176 (c) 174
  31. 31.What is 12³? =
  32. 32.Which of these is a perfect cube? (a) 1288 (b) 1000 (c) 1042
  33. 33.What is ∛3375? =
  34. 34.Which of these is a perfect cube? (a) 1821 (b) 1728 (c) 1809
  35. 35.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  36. 36.What is 7³? =
  37. 37.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  38. 38.What is 14³? =
  39. 39.What is ∛512? =
  40. 40.What is ∛8? =

Answer key

  1. 25
  2. 729
  3. 16
  4. 729
  5. 125
  6. 27
  7. 3
  8. 8
  9. 7
  10. 512
  11. 15
  12. 216
  13. 49
  14. 216
  15. 6
  16. 12
  17. 8
  18. 10
  19. 216
  20. 4913
  21. 8
  22. 3375
  23. 18
  24. 19
  25. 4
  26. 4
  27. 27
  28. 27
  29. 27
  30. 125
  31. 1728
  32. 1000
  33. 15
  34. 1728
  35. 64
  36. 343
  37. 125
  38. 2744
  39. 8
  40. 2

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