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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 472 · 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) 343 (b) 345 (c) 356
  2. 2.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  3. 3.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  5. 5.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  6. 6.Which of these is a perfect cube? (a) 1391 (b) 1663 (c) 1331
  7. 7.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  8. 8.What is 3³? =
  9. 9.Which of these is a perfect cube? (a) 125 (b) 186 (c) 189
  10. 10.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  11. 11.What is ∛125? =
  12. 12.Which of these is a perfect cube? (a) 691 (b) 621 (c) 512
  13. 13.What is ∛6859? =
  14. 14.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  15. 15.Which of these is a perfect cube? (a) 66 (b) 64 (c) 76
  16. 16.What is 4³? =
  17. 17.What is ∛12167? =
  18. 18.What is ∛4913? =
  19. 19.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  20. 20.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  21. 21.What is ∛13824? =
  22. 22.What is 10³? =
  23. 23.Which of these is a perfect cube? (a) 2804 (b) 2744 (c) 2998
  24. 24.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  25. 25.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  26. 26.What is 16³? =
  27. 27.What is ∛216? =
  28. 28.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  29. 29.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  30. 30.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  31. 31.What is ∛15625? =
  32. 32.What is 9³? =
  33. 33.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  35. 35.What is ∛10648? =
  36. 36.What is 5³? =
  37. 37.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  38. 38.What is ∛5832? =
  39. 39.What is ∛1000? =
  40. 40.What is 6³? =

Answer key

  1. 343
  2. 8
  3. 8
  4. 2
  5. 17
  6. 1331
  7. 7
  8. 27
  9. 125
  10. 9
  11. 5
  12. 512
  13. 19
  14. 5
  15. 64
  16. 64
  17. 23
  18. 17
  19. 8
  20. 4
  21. 24
  22. 1000
  23. 2744
  24. 4
  25. 27
  26. 4096
  27. 6
  28. 2
  29. 4
  30. 125
  31. 25
  32. 729
  33. 125
  34. 25
  35. 22
  36. 125
  37. 9
  38. 18
  39. 10
  40. 216

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