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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 491 · 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 cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  2. 2.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  3. 3.What is 7³? =
  4. 4.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  5. 5.What is ∛216? =
  6. 6.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.Which of these is a perfect cube? (a) 3563 (b) 3649 (c) 3375
  8. 8.Which of these is a perfect cube? (a) 687 (b) 512 (c) 673
  9. 9.What is ∛512? =
  10. 10.Which of these is a perfect cube? (a) 323 (b) 237 (c) 216
  11. 11.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  12. 12.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  13. 13.What is 19³? =
  14. 14.What is ∛9261? =
  15. 15.Which of these is a perfect cube? (a) 401 (b) 343 (c) 376
  16. 16.What is ∛4096? =
  17. 17.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  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.Which of these is a perfect cube? (a) 2507 (b) 2375 (c) 2197
  20. 20.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  21. 21.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  22. 22.What is the smallest whole number by which 135 must be divided to get a perfect cube?
  23. 23.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  25. 25.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  26. 26.What is 10³? =
  27. 27.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.What is 20³? =
  31. 31.What is 15³? =
  32. 32.Which of these is a perfect cube? (a) 2102 (b) 1854 (c) 1728
  33. 33.Which of these is a perfect cube? (a) 79 (b) 74 (c) 64
  34. 34.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  35. 35.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  36. 36.What is ∛125? =
  37. 37.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  38. 38.What is 9³? =
  39. 39.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  40. 40.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?

Answer key

  1. 11
  2. 8
  3. 343
  4. 27
  5. 6
  6. 64
  7. 3375
  8. 512
  9. 8
  10. 216
  11. 5
  12. 8
  13. 6859
  14. 21
  15. 343
  16. 16
  17. 19
  18. 8
  19. 2197
  20. 2
  21. 5
  22. 5
  23. 216
  24. 3
  25. 4
  26. 1000
  27. 4
  28. 27
  29. 216
  30. 8000
  31. 3375
  32. 1728
  33. 64
  34. 125
  35. 13
  36. 5
  37. 6
  38. 729
  39. 25
  40. 3

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