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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 391 · 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 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 64 (b) 99 (c) 71
  3. 3.What is ∛64? =
  4. 4.Which of these is a perfect cube? (a) 1160 (b) 1123 (c) 1000
  5. 5.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  6. 6.What is 20³? =
  7. 7.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.Which of these is a perfect cube? (a) 512 (b) 596 (c) 587
  10. 10.What is ∛125? =
  11. 11.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  13. 13.What is ∛729? =
  14. 14.What is ∛1000? =
  15. 15.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  16. 16.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  17. 17.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.Which of these is a perfect cube? (a) 129 (b) 198 (c) 125
  19. 19.What is ∛8? =
  20. 20.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  21. 21.What is 17³? =
  22. 22.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  23. 23.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  24. 24.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  25. 25.What is 4³? =
  26. 26.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  27. 27.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  28. 28.What is 6³? =
  29. 29.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.What is 3³? =
  31. 31.What is ∛512? =
  32. 32.What is ∛2197? =
  33. 33.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  34. 34.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  35. 35.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  36. 36.What is ∛5832? =
  37. 37.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  38. 38.What is ∛9261? =
  39. 39.What is 14³? =
  40. 40.What is ∛8000? =

Answer key

  1. 27
  2. 64
  3. 4
  4. 1000
  5. 49
  6. 8000
  7. 216
  8. 8
  9. 512
  10. 5
  11. 216
  12. 49
  13. 9
  14. 10
  15. 2
  16. 13
  17. 8
  18. 125
  19. 2
  20. 2
  21. 4913
  22. 125
  23. 11
  24. 25
  25. 64
  26. 125
  27. 20
  28. 216
  29. 125
  30. 27
  31. 8
  32. 13
  33. 9
  34. 2
  35. 49
  36. 18
  37. 64
  38. 21
  39. 2744
  40. 20

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