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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 297 · 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 ∛8? =
  2. 2.What is ∛13824? =
  3. 3.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  5. 5.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  6. 6.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  7. 7.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.What is ∛64? =
  10. 10.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  11. 11.What is ∛3375? =
  12. 12.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  14. 14.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.Which of these is a perfect cube? (a) 265 (b) 216 (c) 319
  16. 16.What is ∛125? =
  17. 17.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  18. 18.What is 9³? =
  19. 19.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  20. 20.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  21. 21.Which of these is a perfect cube? (a) 100 (b) 84 (c) 64
  22. 22.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  23. 23.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 47 (b) 30 (c) 27
  25. 25.What is 18³? =
  26. 26.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  27. 27.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  29. 29.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  30. 30.What is ∛216? =
  31. 31.What is ∛9261? =
  32. 32.Which of these is a perfect cube? (a) 2744 (b) 3130 (c) 2848
  33. 33.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.What is ∛2744? =
  35. 35.What is ∛1000? =
  36. 36.What is ∛512? =
  37. 37.What is 8³? =
  38. 38.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  39. 39.What is ∛729? =
  40. 40.What is the smallest whole number by which 576 must be divided to get a perfect cube?

Answer key

  1. 2
  2. 24
  3. 27
  4. 4
  5. 3
  6. 3
  7. 64
  8. 27
  9. 4
  10. 6
  11. 15
  12. 10
  13. 2
  14. 8
  15. 216
  16. 5
  17. 3
  18. 729
  19. 7
  20. 3
  21. 64
  22. 7
  23. 18
  24. 27
  25. 5832
  26. 3
  27. 125
  28. 5
  29. 17
  30. 6
  31. 21
  32. 2744
  33. 125
  34. 14
  35. 10
  36. 8
  37. 512
  38. 4
  39. 9
  40. 9

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