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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 313 · 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 multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  3. 3.What is 19³? =
  4. 4.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  5. 5.What is ∛3375? =
  6. 6.What is ∛4913? =
  7. 7.Which of these is a perfect cube? (a) 1162 (b) 1000 (c) 1045
  8. 8.What is 4³? =
  9. 9.What is ∛512? =
  10. 10.Which of these is a perfect cube? (a) 702 (b) 512 (c) 662
  11. 11.What is ∛343? =
  12. 12.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  13. 13.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  14. 14.What is ∛1000? =
  15. 15.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  16. 16.What is 3³? =
  17. 17.What is 13³? =
  18. 18.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.What is 18³? =
  20. 20.Which of these is a perfect cube? (a) 343 (b) 420 (c) 353
  21. 21.Which of these is a perfect cube? (a) 729 (b) 834 (c) 817
  22. 22.What is ∛4096? =
  23. 23.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  24. 24.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  25. 25.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  26. 26.Which of these is a perfect cube? (a) 1629 (b) 1331 (c) 1537
  27. 27.Which of these is a perfect cube? (a) 295 (b) 305 (c) 216
  28. 28.Which of these is a perfect cube? (a) 40 (b) 27 (c) 35
  29. 29.What is ∛2744? =
  30. 30.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  32. 32.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is 10³? =
  34. 34.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.What is 12³? =
  36. 36.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  37. 37.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  38. 38.What is ∛6859? =
  39. 39.What is ∛125? =
  40. 40.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 5
  2. 25
  3. 6859
  4. 64
  5. 15
  6. 17
  7. 1000
  8. 64
  9. 8
  10. 512
  11. 7
  12. 2
  13. 4
  14. 10
  15. 5
  16. 27
  17. 2197
  18. 8
  19. 5832
  20. 343
  21. 729
  22. 16
  23. 6
  24. 9
  25. 13
  26. 1331
  27. 216
  28. 27
  29. 14
  30. 125
  31. 5
  32. 216
  33. 1000
  34. 27
  35. 1728
  36. 27
  37. 4
  38. 19
  39. 5
  40. 216

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