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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 485 · 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) 79 (b) 87 (c) 64
  2. 2.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  3. 3.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  4. 4.What is 15³? =
  5. 5.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  6. 6.What is ∛1331? =
  7. 7.Which of these is a perfect cube? (a) 512 (b) 670 (c) 576
  8. 8.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  9. 9.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.What is 7³? =
  11. 11.Which of these is a perfect cube? (a) 3405 (b) 3375 (c) 3381
  12. 12.What is ∛1728? =
  13. 13.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  14. 14.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  15. 15.Which of these is a perfect cube? (a) 2744 (b) 3049 (c) 3254
  16. 16.What is 16³? =
  17. 17.What is 18³? =
  18. 18.Which of these is a perfect cube? (a) 751 (b) 729 (c) 862
  19. 19.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  20. 20.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  22. 22.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  23. 23.What is ∛729? =
  24. 24.What is 8³? =
  25. 25.What is ∛27? =
  26. 26.Which of these is a perfect cube? (a) 125 (b) 146 (c) 184
  27. 27.What is ∛10648? =
  28. 28.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  29. 29.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 241 (b) 219 (c) 216
  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.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  33. 33.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  34. 34.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.What is ∛4096? =
  36. 36.What is 17³? =
  37. 37.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  38. 38.What is 4³? =
  39. 39.What is ∛125? =
  40. 40.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?

Answer key

  1. 64
  2. 7
  3. 4
  4. 3375
  5. 3
  6. 11
  7. 512
  8. 5
  9. 125
  10. 343
  11. 3375
  12. 12
  13. 5
  14. 2
  15. 2744
  16. 4096
  17. 5832
  18. 729
  19. 16
  20. 6
  21. 216
  22. 9
  23. 9
  24. 512
  25. 3
  26. 125
  27. 22
  28. 4
  29. 125
  30. 216
  31. 27
  32. 25
  33. 8
  34. 27
  35. 16
  36. 4913
  37. 9
  38. 64
  39. 5
  40. 2

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