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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 205 · 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 ∛13824? =
  2. 2.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  3. 3.What is ∛27? =
  4. 4.What is ∛4913? =
  5. 5.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  6. 6.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  7. 7.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  8. 8.What is 4³? =
  9. 9.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.Which of these is a perfect cube? (a) 1549 (b) 1331 (c) 1550
  11. 11.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  13. 13.Which of these is a perfect cube? (a) 3150 (b) 3284 (c) 2744
  14. 14.What is ∛2744? =
  15. 15.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  16. 16.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  17. 17.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  18. 18.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  19. 19.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  20. 20.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  21. 21.What is ∛729? =
  22. 22.Which of these is a perfect cube? (a) 42 (b) 27 (c) 52
  23. 23.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  24. 24.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.Which of these is a perfect cube? (a) 2197 (b) 2470 (c) 2315
  26. 26.What is 7³? =
  27. 27.Which of these is a perfect cube? (a) 142 (b) 190 (c) 125
  28. 28.What is ∛8? =
  29. 29.What is ∛1000? =
  30. 30.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  31. 31.What is 16³? =
  32. 32.What is ∛3375? =
  33. 33.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.Which of these is a perfect cube? (a) 1043 (b) 1000 (c) 1179
  35. 35.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  36. 36.What is 12³? =
  37. 37.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  38. 38.What is 17³? =
  39. 39.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  40. 40.What is ∛15625? =

Answer key

  1. 24
  2. 5
  3. 3
  4. 17
  5. 15
  6. 11
  7. 125
  8. 64
  9. 216
  10. 1331
  11. 27
  12. 14
  13. 2744
  14. 14
  15. 4
  16. 9
  17. 16
  18. 27
  19. 27
  20. 3
  21. 9
  22. 27
  23. 4
  24. 216
  25. 2197
  26. 343
  27. 125
  28. 2
  29. 10
  30. 19
  31. 4096
  32. 15
  33. 8
  34. 1000
  35. 4
  36. 1728
  37. 4
  38. 4913
  39. 9
  40. 25

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