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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 335 · 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 675 must be divided to get a perfect cube?
  2. 2.What is 16³? =
  3. 3.What is 7³? =
  4. 4.What is 13³? =
  5. 5.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  6. 6.What is 20³? =
  7. 7.Which of these is a perfect cube? (a) 316 (b) 280 (c) 216
  8. 8.What is ∛343? =
  9. 9.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  10. 10.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  11. 11.What is 17³? =
  12. 12.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.What is 11³? =
  14. 14.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is ∛27? =
  16. 16.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  17. 17.What is ∛2744? =
  18. 18.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  19. 19.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is ∛125? =
  21. 21.What is 9³? =
  22. 22.Which of these is a perfect cube? (a) 1434 (b) 1337 (c) 1331
  23. 23.Which of these is a perfect cube? (a) 729 (b) 731 (c) 854
  24. 24.What is ∛729? =
  25. 25.Which of these is a perfect cube? (a) 41 (b) 44 (c) 27
  26. 26.What is 15³? =
  27. 27.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  28. 28.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  30. 30.Which of these is a perfect cube? (a) 347 (b) 343 (c) 357
  31. 31.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  32. 32.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  33. 33.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  34. 34.What is 2³? =
  35. 35.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  38. 38.Which of these is a perfect cube? (a) 1198 (b) 1115 (c) 1000
  39. 39.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  40. 40.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?

Answer key

  1. 25
  2. 4096
  3. 343
  4. 2197
  5. 9
  6. 8000
  7. 216
  8. 7
  9. 11
  10. 20
  11. 4913
  12. 125
  13. 1331
  14. 216
  15. 3
  16. 8
  17. 14
  18. 8
  19. 64
  20. 5
  21. 729
  22. 1331
  23. 729
  24. 9
  25. 27
  26. 3375
  27. 3
  28. 27
  29. 25
  30. 343
  31. 64
  32. 49
  33. 2
  34. 8
  35. 49
  36. 9
  37. 15
  38. 1000
  39. 64
  40. 10

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