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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 993 · 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.Which of these is a perfect cube? (a) 512 (b) 521 (c) 566
  2. 2.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  4. 4.What is 12³? =
  5. 5.What is ∛8? =
  6. 6.What is ∛9261? =
  7. 7.What is ∛4913? =
  8. 8.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.What is 5³? =
  10. 10.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is ∛10648? =
  12. 12.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  13. 13.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  14. 14.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  15. 15.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  17. 17.What is 20³? =
  18. 18.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.Which of these is a perfect cube? (a) 1785 (b) 1728 (c) 2067
  20. 20.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  23. 23.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  24. 24.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  25. 25.What is ∛13824? =
  26. 26.What is ∛5832? =
  27. 27.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.What is 14³? =
  29. 29.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.What is 4³? =
  31. 31.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  32. 32.Which of these is a perfect cube? (a) 876 (b) 729 (c) 809
  33. 33.What is ∛2197? =
  34. 34.Which of these is a perfect cube? (a) 3559 (b) 3959 (c) 3375
  35. 35.Which of these is a perfect cube? (a) 144 (b) 149 (c) 125
  36. 36.What is ∛2744? =
  37. 37.Which of these is a perfect cube? (a) 395 (b) 420 (c) 343
  38. 38.What is ∛512? =
  39. 39.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  40. 40.What is 9³? =

Answer key

  1. 512
  2. 125
  3. 25
  4. 1728
  5. 2
  6. 21
  7. 17
  8. 125
  9. 125
  10. 125
  11. 22
  12. 5
  13. 64
  14. 7
  15. 64
  16. 6
  17. 8000
  18. 64
  19. 1728
  20. 9
  21. 8
  22. 9
  23. 4
  24. 7
  25. 24
  26. 18
  27. 27
  28. 2744
  29. 8
  30. 64
  31. 3
  32. 729
  33. 13
  34. 3375
  35. 125
  36. 14
  37. 343
  38. 8
  39. 216
  40. 729

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