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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 131 · 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 16 must be multiplied to get a perfect cube?
  2. 2.Which of these is a perfect cube? (a) 1000 (b) 1282 (c) 1162
  3. 3.What is 2³? =
  4. 4.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  5. 5.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  6. 6.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.What is 17³? =
  9. 9.What is ∛12167? =
  10. 10.Which of these is a perfect cube? (a) 729 (b) 733 (c) 776
  11. 11.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  12. 12.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  13. 13.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  14. 14.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  15. 15.What is 13³? =
  16. 16.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  17. 17.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  18. 18.What is 14³? =
  19. 19.What is 8³? =
  20. 20.What is ∛9261? =
  21. 21.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  22. 22.What is 4³? =
  23. 23.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  24. 24.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  25. 25.What is ∛64? =
  26. 26.What is ∛1331? =
  27. 27.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  28. 28.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  29. 29.Which of these is a perfect cube? (a) 512 (b) 647 (c) 568
  30. 30.Which of these is a perfect cube? (a) 1331 (b) 1689 (c) 1675
  31. 31.What is 18³? =
  32. 32.What is ∛15625? =
  33. 33.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.What is ∛27? =
  35. 35.What is ∛1000? =
  36. 36.What is 16³? =
  37. 37.What is 6³? =
  38. 38.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  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 5³? =

Answer key

  1. 4
  2. 1000
  3. 8
  4. 5
  5. 3
  6. 216
  7. 8
  8. 4913
  9. 23
  10. 729
  11. 2
  12. 49
  13. 49
  14. 9
  15. 2197
  16. 8
  17. 7
  18. 2744
  19. 512
  20. 21
  21. 4
  22. 64
  23. 17
  24. 7
  25. 4
  26. 11
  27. 4
  28. 3
  29. 512
  30. 1331
  31. 5832
  32. 25
  33. 27
  34. 3
  35. 10
  36. 4096
  37. 216
  38. 49
  39. 216
  40. 125

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