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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 94 · 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 7³? =
  2. 2.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  3. 3.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  4. 4.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  5. 5.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  6. 6.What is 15³? =
  7. 7.What is 5³? =
  8. 8.What is ∛1331? =
  9. 9.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  11. 11.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.Which of these is a perfect cube? (a) 729 (b) 748 (c) 892
  13. 13.What is ∛512? =
  14. 14.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  15. 15.What is ∛343? =
  16. 16.What is ∛4913? =
  17. 17.Which of these is a perfect cube? (a) 32 (b) 27 (c) 34
  18. 18.Which of these is a perfect cube? (a) 1000 (b) 1088 (c) 1164
  19. 19.What is 2³? =
  20. 20.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  21. 21.Which of these is a perfect cube? (a) 686 (b) 519 (c) 512
  22. 22.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  23. 23.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  24. 24.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  25. 25.What is 6³? =
  26. 26.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  27. 27.What is 17³? =
  28. 28.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  29. 29.Which of these is a perfect cube? (a) 89 (b) 64 (c) 88
  30. 30.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  31. 31.Which of these is a perfect cube? (a) 396 (b) 407 (c) 343
  32. 32.What is 4³? =
  33. 33.What is ∛10648? =
  34. 34.What is ∛2197? =
  35. 35.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  36. 36.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  37. 37.What is ∛1000? =
  38. 38.Which of these is a perfect cube? (a) 1845 (b) 1743 (c) 1728
  39. 39.Which of these is a perfect cube? (a) 2570 (b) 2316 (c) 2197
  40. 40.What is the smallest whole number by which 2 must be divided to get a perfect cube?

Answer key

  1. 343
  2. 2
  3. 15
  4. 3
  5. 25
  6. 3375
  7. 125
  8. 11
  9. 8
  10. 8
  11. 216
  12. 729
  13. 8
  14. 49
  15. 7
  16. 17
  17. 27
  18. 1000
  19. 8
  20. 125
  21. 512
  22. 5
  23. 27
  24. 27
  25. 216
  26. 18
  27. 4913
  28. 5
  29. 64
  30. 17
  31. 343
  32. 64
  33. 22
  34. 13
  35. 2
  36. 20
  37. 10
  38. 1728
  39. 2197
  40. 2

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