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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 799 · 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) 27 (b) 38 (c) 42
  2. 2.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  3. 3.What is ∛64? =
  4. 4.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  5. 5.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  6. 6.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.What is 10³? =
  8. 8.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.What is 18³? =
  10. 10.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  11. 11.What is ∛1000? =
  12. 12.What is ∛343? =
  13. 13.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  14. 14.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  15. 15.What is 12³? =
  16. 16.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  17. 17.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  18. 18.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  19. 19.What is ∛216? =
  20. 20.What is 5³? =
  21. 21.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛4913? =
  23. 23.What is 19³? =
  24. 24.What is 11³? =
  25. 25.What is ∛8000? =
  26. 26.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  27. 27.What is 9³? =
  28. 28.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  29. 29.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 154 (b) 150 (c) 125
  31. 31.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  32. 32.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  33. 33.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  34. 34.What is ∛12167? =
  35. 35.What is 20³? =
  36. 36.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  37. 37.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  38. 38.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  39. 39.Which of these is a perfect cube? (a) 343 (b) 344 (c) 483
  40. 40.Which of these is a perfect cube? (a) 3072 (b) 2744 (c) 3036

Answer key

  1. 27
  2. 7
  3. 4
  4. 8
  5. 7
  6. 125
  7. 1000
  8. 125
  9. 5832
  10. 9
  11. 10
  12. 7
  13. 216
  14. 17
  15. 1728
  16. 5
  17. 4
  18. 12
  19. 6
  20. 125
  21. 5
  22. 17
  23. 6859
  24. 1331
  25. 20
  26. 19
  27. 729
  28. 7
  29. 216
  30. 125
  31. 4
  32. 5
  33. 18
  34. 23
  35. 8000
  36. 13
  37. 125
  38. 2
  39. 343
  40. 2744

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