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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 565 · 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 big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 181 (b) 125 (c) 134
  3. 3.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  5. 5.What is ∛6859? =
  6. 6.What is 15³? =
  7. 7.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.What is 17³? =
  10. 10.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  11. 11.Which of these is a perfect cube? (a) 2128 (b) 1728 (c) 1776
  12. 12.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  13. 13.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  14. 14.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  15. 15.What is ∛1728? =
  16. 16.What is 18³? =
  17. 17.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  18. 18.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is 16³? =
  21. 21.What is ∛3375? =
  22. 22.What is ∛13824? =
  23. 23.What is 4³? =
  24. 24.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  25. 25.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  26. 26.What is 10³? =
  27. 27.Which of these is a perfect cube? (a) 400 (b) 343 (c) 417
  28. 28.What is 14³? =
  29. 29.What is 12³? =
  30. 30.What is ∛512? =
  31. 31.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  32. 32.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  33. 33.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  34. 34.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 2962 (b) 2744 (c) 2911
  36. 36.Which of these is a perfect cube? (a) 216 (b) 240 (c) 251
  37. 37.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  38. 38.What is ∛8? =
  39. 39.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.What is 9³? =

Answer key

  1. 8
  2. 125
  3. 64
  4. 7
  5. 19
  6. 3375
  7. 216
  8. 216
  9. 4913
  10. 9
  11. 1728
  12. 3
  13. 7
  14. 5
  15. 12
  16. 5832
  17. 3
  18. 125
  19. 125
  20. 4096
  21. 15
  22. 24
  23. 64
  24. 2
  25. 17
  26. 1000
  27. 343
  28. 2744
  29. 1728
  30. 8
  31. 27
  32. 216
  33. 25
  34. 7
  35. 2744
  36. 216
  37. 9
  38. 2
  39. 8
  40. 729

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