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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 924 · 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 648 must be multiplied to get a perfect cube?
  2. 2.What is 20³? =
  3. 3.What is 15³? =
  4. 4.What is ∛5832? =
  5. 5.Which of these is a perfect cube? (a) 225 (b) 323 (c) 216
  6. 6.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  7. 7.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  10. 10.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  11. 11.What is 9³? =
  12. 12.What is 7³? =
  13. 13.What is 10³? =
  14. 14.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  15. 15.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  16. 16.What is ∛4096? =
  17. 17.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  18. 18.What is 14³? =
  19. 19.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  20. 20.What is 3³? =
  21. 21.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  22. 22.What is ∛8? =
  23. 23.Which of these is a perfect cube? (a) 1390 (b) 1331 (c) 1487
  24. 24.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  25. 25.What is ∛27? =
  26. 26.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  27. 27.Which of these is a perfect cube? (a) 38 (b) 34 (c) 27
  28. 28.Which of these is a perfect cube? (a) 1006 (b) 1178 (c) 1000
  29. 29.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  30. 30.What is 6³? =
  31. 31.Which of these is a perfect cube? (a) 3103 (b) 2861 (c) 2744
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is 16³? =
  34. 34.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  35. 35.What is 5³? =
  36. 36.What is 11³? =
  37. 37.Which of these is a perfect cube? (a) 2126 (b) 2105 (c) 1728
  38. 38.What is ∛2744? =
  39. 39.What is ∛10648? =
  40. 40.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 9
  2. 8000
  3. 3375
  4. 18
  5. 216
  6. 4
  7. 8
  8. 2
  9. 2
  10. 3
  11. 729
  12. 343
  13. 1000
  14. 49
  15. 15
  16. 16
  17. 7
  18. 2744
  19. 64
  20. 27
  21. 8
  22. 2
  23. 1331
  24. 4
  25. 3
  26. 3
  27. 27
  28. 1000
  29. 19
  30. 216
  31. 2744
  32. 8
  33. 4096
  34. 7
  35. 125
  36. 1331
  37. 1728
  38. 14
  39. 22
  40. 8

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