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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 872 · 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 6³? =
  2. 2.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  3. 3.What is ∛9261? =
  4. 4.What is 3³? =
  5. 5.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  6. 6.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  7. 7.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  8. 8.What is 19³? =
  9. 9.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.Which of these is a perfect cube? (a) 3784 (b) 3375 (c) 3969
  11. 11.What is ∛27? =
  12. 12.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  13. 13.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  14. 14.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  16. 16.What is ∛216? =
  17. 17.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  18. 18.Which of these is a perfect cube? (a) 1124 (b) 1000 (c) 1088
  19. 19.Which of these is a perfect cube? (a) 383 (b) 343 (c) 427
  20. 20.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  21. 21.What is 14³? =
  22. 22.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  23. 23.What is ∛343? =
  24. 24.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  25. 25.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  26. 26.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  27. 27.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.What is ∛1728? =
  29. 29.What is ∛6859? =
  30. 30.What is ∛2197? =
  31. 31.What is 18³? =
  32. 32.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  33. 33.Which of these is a perfect cube? (a) 134 (b) 125 (c) 196
  34. 34.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  36. 36.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  37. 37.What is 12³? =
  38. 38.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  39. 39.What is ∛64? =
  40. 40.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?

Answer key

  1. 216
  2. 125
  3. 21
  4. 27
  5. 49
  6. 25
  7. 4
  8. 6859
  9. 125
  10. 3375
  11. 3
  12. 4
  13. 5
  14. 27
  15. 18
  16. 6
  17. 25
  18. 1000
  19. 343
  20. 8
  21. 2744
  22. 25
  23. 7
  24. 3
  25. 10
  26. 5
  27. 64
  28. 12
  29. 19
  30. 13
  31. 5832
  32. 15
  33. 125
  34. 125
  35. 17
  36. 9
  37. 1728
  38. 49
  39. 4
  40. 9

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