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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 812 · 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 40 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  3. 3.What is ∛2744? =
  4. 4.Which of these is a perfect cube? (a) 36 (b) 27 (c) 42
  5. 5.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.What is ∛13824? =
  7. 7.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  8. 8.What is 8³? =
  9. 9.Which of these is a perfect cube? (a) 68 (b) 73 (c) 64
  10. 10.What is ∛343? =
  11. 11.What is ∛1331? =
  12. 12.What is 2³? =
  13. 13.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  14. 14.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  15. 15.Which of these is a perfect cube? (a) 865 (b) 729 (c) 822
  16. 16.What is ∛6859? =
  17. 17.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  18. 18.What is ∛4096? =
  19. 19.What is ∛9261? =
  20. 20.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  21. 21.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  22. 22.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  23. 23.What is 6³? =
  24. 24.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  25. 25.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  26. 26.What is 10³? =
  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 7³? =
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  31. 31.Which of these is a perfect cube? (a) 216 (b) 265 (c) 230
  32. 32.Which of these is a perfect cube? (a) 2422 (b) 2197 (c) 2664
  33. 33.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  34. 34.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  35. 35.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.What is 20³? =
  37. 37.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  38. 38.Which of these is a perfect cube? (a) 480 (b) 473 (c) 343
  39. 39.Which of these is a perfect cube? (a) 148 (b) 199 (c) 125
  40. 40.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?

Answer key

  1. 25
  2. 5
  3. 14
  4. 27
  5. 8
  6. 24
  7. 10
  8. 512
  9. 64
  10. 7
  11. 11
  12. 8
  13. 64
  14. 8
  15. 729
  16. 19
  17. 125
  18. 16
  19. 21
  20. 2
  21. 9
  22. 4
  23. 216
  24. 2
  25. 216
  26. 1000
  27. 27
  28. 343
  29. 216
  30. 4
  31. 216
  32. 2197
  33. 25
  34. 14
  35. 125
  36. 8000
  37. 25
  38. 343
  39. 125
  40. 3

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