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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 785 · 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 1125 must be divided to get a perfect cube?
  2. 2.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  3. 3.What is ∛216? =
  4. 4.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.Which of these is a perfect cube? (a) 42 (b) 30 (c) 27
  6. 6.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  7. 7.What is 17³? =
  8. 8.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  10. 10.What is ∛3375? =
  11. 11.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.Which of these is a perfect cube? (a) 2744 (b) 2847 (c) 3306
  13. 13.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  14. 14.What is ∛2744? =
  15. 15.What is ∛1331? =
  16. 16.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  17. 17.What is ∛10648? =
  18. 18.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  19. 19.Which of these is a perfect cube? (a) 2089 (b) 1728 (c) 1982
  20. 20.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  21. 21.What is ∛64? =
  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.What is 7³? =
  24. 24.What is 19³? =
  25. 25.What is 3³? =
  26. 26.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  27. 27.What is ∛1000? =
  28. 28.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛125? =
  30. 30.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  31. 31.What is 2³? =
  32. 32.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  33. 33.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  34. 34.Which of these is a perfect cube? (a) 168 (b) 155 (c) 125
  35. 35.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  37. 37.What is 8³? =
  38. 38.What is ∛5832? =
  39. 39.What is ∛8? =
  40. 40.What is ∛9261? =

Answer key

  1. 9
  2. 125
  3. 6
  4. 125
  5. 27
  6. 5
  7. 4913
  8. 20
  9. 5
  10. 15
  11. 64
  12. 2744
  13. 4
  14. 14
  15. 11
  16. 4
  17. 22
  18. 5
  19. 1728
  20. 4
  21. 4
  22. 125
  23. 343
  24. 6859
  25. 27
  26. 4
  27. 10
  28. 12
  29. 5
  30. 49
  31. 8
  32. 18
  33. 17
  34. 125
  35. 216
  36. 13
  37. 512
  38. 18
  39. 2
  40. 21

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