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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 940 · 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 cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  2. 2.What is ∛4096? =
  3. 3.What is 9³? =
  4. 4.What is ∛5832? =
  5. 5.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.A big cube of edge 15 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 9 must be multiplied to get a perfect cube?
  8. 8.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  9. 9.What is ∛512? =
  10. 10.What is ∛2744? =
  11. 11.What is ∛9261? =
  12. 12.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  14. 14.What is 4³? =
  15. 15.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 1030 (b) 1010 (c) 1000
  17. 17.What is 5³? =
  18. 18.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  19. 19.What is ∛1000? =
  20. 20.What is ∛8000? =
  21. 21.Which of these is a perfect cube? (a) 2895 (b) 2964 (c) 2744
  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 64 cubic cm. How long is each edge (in cm)?
  24. 24.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.What is 14³? =
  26. 26.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  28. 28.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  29. 29.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.What is 7³? =
  31. 31.What is ∛3375? =
  32. 32.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  33. 33.Which of these is a perfect cube? (a) 802 (b) 734 (c) 729
  34. 34.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  35. 35.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.What is 16³? =
  37. 37.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  38. 38.Which of these is a perfect cube? (a) 556 (b) 512 (c) 564
  39. 39.What is ∛64? =
  40. 40.Which of these is a perfect cube? (a) 2255 (b) 2197 (c) 2515

Answer key

  1. 9
  2. 16
  3. 729
  4. 18
  5. 125
  6. 125
  7. 3
  8. 5
  9. 8
  10. 14
  11. 21
  12. 8
  13. 7
  14. 64
  15. 2
  16. 1000
  17. 125
  18. 216
  19. 10
  20. 20
  21. 2744
  22. 125
  23. 4
  24. 64
  25. 2744
  26. 8
  27. 3
  28. 11
  29. 64
  30. 343
  31. 15
  32. 8
  33. 729
  34. 4
  35. 27
  36. 4096
  37. 8
  38. 512
  39. 4
  40. 2197

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