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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 285 · 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 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  3. 3.What is 9³? =
  4. 4.What is 8³? =
  5. 5.Which of these is a perfect cube? (a) 193 (b) 125 (c) 180
  6. 6.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  7. 7.What is ∛4913? =
  8. 8.What is 7³? =
  9. 9.What is ∛27? =
  10. 10.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.Which of these is a perfect cube? (a) 1806 (b) 2058 (c) 1728
  12. 12.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  13. 13.What is ∛4096? =
  14. 14.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  15. 15.Which of these is a perfect cube? (a) 4005 (b) 3640 (c) 3375
  16. 16.What is 17³? =
  17. 17.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  18. 18.What is 12³? =
  19. 19.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  20. 20.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  21. 21.What is ∛8? =
  22. 22.Which of these is a perfect cube? (a) 2299 (b) 2197 (c) 2268
  23. 23.What is ∛64? =
  24. 24.What is ∛125? =
  25. 25.What is 16³? =
  26. 26.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  27. 27.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  28. 28.What is 2³? =
  29. 29.Which of these is a perfect cube? (a) 111 (b) 64 (c) 91
  30. 30.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  31. 31.What is 14³? =
  32. 32.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  33. 33.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  35. 35.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  37. 37.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.What is 3³? =
  39. 39.What is ∛216? =
  40. 40.What is 6³? =

Answer key

  1. 125
  2. 49
  3. 729
  4. 512
  5. 125
  6. 8
  7. 17
  8. 343
  9. 3
  10. 27
  11. 1728
  12. 4
  13. 16
  14. 7
  15. 3375
  16. 4913
  17. 17
  18. 1728
  19. 49
  20. 8
  21. 2
  22. 2197
  23. 4
  24. 5
  25. 4096
  26. 4
  27. 4
  28. 8
  29. 64
  30. 27
  31. 2744
  32. 49
  33. 216
  34. 5
  35. 125
  36. 9
  37. 216
  38. 27
  39. 6
  40. 216

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