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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 905 · 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.Which of these is a perfect cube? (a) 2744 (b) 3313 (c) 2861
  2. 2.What is 5³? =
  3. 3.What is 4³? =
  4. 4.What is ∛27? =
  5. 5.What is 3³? =
  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.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  8. 8.What is ∛8000? =
  9. 9.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  10. 10.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  11. 11.Which of these is a perfect cube? (a) 103 (b) 107 (c) 64
  12. 12.Which of these is a perfect cube? (a) 181 (b) 158 (c) 125
  13. 13.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  14. 14.What is ∛125? =
  15. 15.Which of these is a perfect cube? (a) 2299 (b) 2374 (c) 2197
  16. 16.What is 13³? =
  17. 17.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  18. 18.What is 16³? =
  19. 19.What is ∛4913? =
  20. 20.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  21. 21.What is 11³? =
  22. 22.Which of these is a perfect cube? (a) 942 (b) 955 (c) 729
  23. 23.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  24. 24.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  25. 25.What is 6³? =
  26. 26.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  27. 27.Which of these is a perfect cube? (a) 295 (b) 216 (c) 230
  28. 28.What is 18³? =
  29. 29.What is 12³? =
  30. 30.What is 8³? =
  31. 31.What is 17³? =
  32. 32.A big cube of edge 8 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 10584 must be divided to get a perfect cube?
  34. 34.What is ∛13824? =
  35. 35.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  36. 36.Which of these is a perfect cube? (a) 1331 (b) 1382 (c) 1383
  37. 37.What is ∛729? =
  38. 38.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  40. 40.What is ∛64? =

Answer key

  1. 2744
  2. 125
  3. 64
  4. 3
  5. 27
  6. 8
  7. 125
  8. 20
  9. 11
  10. 5
  11. 64
  12. 125
  13. 3
  14. 5
  15. 2197
  16. 2197
  17. 16
  18. 4096
  19. 17
  20. 64
  21. 1331
  22. 729
  23. 17
  24. 12
  25. 216
  26. 216
  27. 216
  28. 5832
  29. 1728
  30. 512
  31. 4913
  32. 8
  33. 49
  34. 24
  35. 3
  36. 1331
  37. 9
  38. 9
  39. 7
  40. 4

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