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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 729 · 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 20³? =
  2. 2.What is 15³? =
  3. 3.What is ∛729? =
  4. 4.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  5. 5.What is 18³? =
  6. 6.What is ∛216? =
  7. 7.What is ∛125? =
  8. 8.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  9. 9.What is 7³? =
  10. 10.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  11. 11.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  12. 12.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  13. 13.Which of these is a perfect cube? (a) 33 (b) 27 (c) 38
  14. 14.What is 8³? =
  15. 15.What is ∛6859? =
  16. 16.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  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 2³? =
  19. 19.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  20. 20.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  21. 21.What is ∛27? =
  22. 22.What is ∛10648? =
  23. 23.Which of these is a perfect cube? (a) 3047 (b) 2798 (c) 2744
  24. 24.What is ∛2744? =
  25. 25.Which of these is a perfect cube? (a) 2116 (b) 2085 (c) 1728
  26. 26.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.What is ∛1728? =
  28. 28.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  29. 29.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  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 1600 must be multiplied to get a perfect cube?
  32. 32.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  33. 33.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  34. 34.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.Which of these is a perfect cube? (a) 216 (b) 317 (c) 285
  36. 36.What is 9³? =
  37. 37.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  38. 38.Which of these is a perfect cube? (a) 483 (b) 343 (c) 453
  39. 39.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  40. 40.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 8000
  2. 3375
  3. 9
  4. 27
  5. 5832
  6. 6
  7. 5
  8. 9
  9. 343
  10. 7
  11. 216
  12. 6
  13. 27
  14. 512
  15. 19
  16. 12
  17. 216
  18. 8
  19. 125
  20. 25
  21. 3
  22. 22
  23. 2744
  24. 14
  25. 1728
  26. 27
  27. 12
  28. 3
  29. 125
  30. 125
  31. 5
  32. 17
  33. 2
  34. 64
  35. 216
  36. 729
  37. 216
  38. 343
  39. 15
  40. 8

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