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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 818 · 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 14³? =
  2. 2.Which of these is a perfect cube? (a) 2953 (b) 3256 (c) 2744
  3. 3.Which of these is a perfect cube? (a) 173 (b) 172 (c) 125
  4. 4.What is 6³? =
  5. 5.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  6. 6.What is the smallest whole number by which 16 must be divided 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.What is 9³? =
  9. 9.What is ∛12167? =
  10. 10.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is ∛5832? =
  12. 12.Which of these is a perfect cube? (a) 312 (b) 216 (c) 250
  13. 13.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  14. 14.What is ∛125? =
  15. 15.What is 8³? =
  16. 16.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  17. 17.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.What is 10³? =
  19. 19.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  20. 20.What is 12³? =
  21. 21.What is ∛27? =
  22. 22.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  23. 23.What is ∛1728? =
  24. 24.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  25. 25.What is ∛8000? =
  26. 26.What is 7³? =
  27. 27.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.Which of these is a perfect cube? (a) 512 (b) 519 (c) 630
  29. 29.What is 4³? =
  30. 30.Which of these is a perfect cube? (a) 2278 (b) 2197 (c) 2207
  31. 31.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  32. 32.What is ∛343? =
  33. 33.What is 2³? =
  34. 34.What is ∛6859? =
  35. 35.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  36. 36.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is 19³? =
  38. 38.What is 15³? =
  39. 39.What is ∛216? =
  40. 40.Which of these is a perfect cube? (a) 3473 (b) 4049 (c) 3375

Answer key

  1. 2744
  2. 2744
  3. 125
  4. 216
  5. 25
  6. 2
  7. 8
  8. 729
  9. 23
  10. 8
  11. 18
  12. 216
  13. 2
  14. 5
  15. 512
  16. 8
  17. 216
  18. 1000
  19. 4
  20. 1728
  21. 3
  22. 4
  23. 12
  24. 64
  25. 20
  26. 343
  27. 27
  28. 512
  29. 64
  30. 2197
  31. 64
  32. 7
  33. 8
  34. 19
  35. 9
  36. 27
  37. 6859
  38. 3375
  39. 6
  40. 3375

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