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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 358 · 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.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  3. 3.What is 11³? =
  4. 4.What is 6³? =
  5. 5.What is 12³? =
  6. 6.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  7. 7.What is 3³? =
  8. 8.What is ∛9261? =
  9. 9.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  10. 10.Which of these is a perfect cube? (a) 729 (b) 824 (c) 753
  11. 11.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  12. 12.Which of these is a perfect cube? (a) 1000 (b) 1288 (c) 1229
  13. 13.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  14. 14.What is 4³? =
  15. 15.Which of these is a perfect cube? (a) 27 (b) 29 (c) 48
  16. 16.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  17. 17.Which of these is a perfect cube? (a) 1728 (b) 1883 (c) 1761
  18. 18.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  20. 20.What is ∛64? =
  21. 21.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  22. 22.What is 8³? =
  23. 23.Which of these is a perfect cube? (a) 97 (b) 72 (c) 64
  24. 24.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.What is ∛343? =
  26. 26.What is ∛1728? =
  27. 27.What is ∛8? =
  28. 28.What is ∛10648? =
  29. 29.What is ∛1000? =
  30. 30.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  31. 31.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  32. 32.What is ∛125? =
  33. 33.What is ∛2744? =
  34. 34.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  35. 35.What is ∛13824? =
  36. 36.Which of these is a perfect cube? (a) 125 (b) 150 (c) 200
  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 the smallest whole number by which 72 must be multiplied to get a perfect cube?
  39. 39.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  40. 40.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 125
  2. 2
  3. 1331
  4. 216
  5. 1728
  6. 216
  7. 27
  8. 21
  9. 3
  10. 729
  11. 8
  12. 1000
  13. 4
  14. 64
  15. 27
  16. 216
  17. 1728
  18. 8
  19. 2
  20. 4
  21. 8
  22. 512
  23. 64
  24. 125
  25. 7
  26. 12
  27. 2
  28. 22
  29. 10
  30. 7
  31. 2
  32. 5
  33. 14
  34. 14
  35. 24
  36. 125
  37. 125
  38. 3
  39. 3
  40. 64

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