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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 92 · 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.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 2237 (b) 2496 (c) 2197
  3. 3.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  4. 4.What is ∛8? =
  5. 5.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  6. 6.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  7. 7.What is ∛8000? =
  8. 8.Which of these is a perfect cube? (a) 900 (b) 814 (c) 729
  9. 9.What is ∛9261? =
  10. 10.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  11. 11.What is 12³? =
  12. 12.What is ∛216? =
  13. 13.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  14. 14.What is ∛125? =
  15. 15.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  16. 16.What is 6³? =
  17. 17.What is 2³? =
  18. 18.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  19. 19.What is 14³? =
  20. 20.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  21. 21.What is 3³? =
  22. 22.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  23. 23.Which of these is a perfect cube? (a) 1728 (b) 1979 (c) 2143
  24. 24.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  25. 25.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  26. 26.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  27. 27.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  28. 28.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  29. 29.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  30. 30.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  31. 31.What is ∛4096? =
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.What is ∛15625? =
  34. 34.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  35. 35.What is 20³? =
  36. 36.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  37. 37.What is ∛1728? =
  38. 38.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.What is ∛343? =
  40. 40.What is ∛1000? =

Answer key

  1. 27
  2. 2197
  3. 20
  4. 2
  5. 13
  6. 216
  7. 20
  8. 729
  9. 21
  10. 9
  11. 1728
  12. 6
  13. 8
  14. 5
  15. 49
  16. 216
  17. 8
  18. 2
  19. 2744
  20. 7
  21. 27
  22. 3
  23. 1728
  24. 5
  25. 4
  26. 7
  27. 4
  28. 2
  29. 49
  30. 49
  31. 16
  32. 27
  33. 25
  34. 18
  35. 8000
  36. 2
  37. 12
  38. 64
  39. 7
  40. 10

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