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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 779 · 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) 2909 (b) 3119 (c) 2744
  2. 2.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  3. 3.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  5. 5.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  6. 6.What is ∛343? =
  7. 7.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  8. 8.Which of these is a perfect cube? (a) 64 (b) 71 (c) 87
  9. 9.What is 8³? =
  10. 10.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  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.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  13. 13.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  14. 14.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  16. 16.What is 10³? =
  17. 17.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  18. 18.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  19. 19.What is ∛2197? =
  20. 20.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  21. 21.Which of these is a perfect cube? (a) 512 (b) 615 (c) 530
  22. 22.Which of these is a perfect cube? (a) 3864 (b) 3508 (c) 3375
  23. 23.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is ∛5832? =
  25. 25.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  26. 26.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  28. 28.What is 4³? =
  29. 29.What is ∛729? =
  30. 30.What is 19³? =
  31. 31.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  32. 32.What is 13³? =
  33. 33.What is ∛13824? =
  34. 34.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.What is ∛6859? =
  36. 36.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  37. 37.What is ∛4913? =
  38. 38.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  39. 39.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  40. 40.What is ∛1728? =

Answer key

  1. 2744
  2. 8
  3. 125
  4. 49
  5. 25
  6. 7
  7. 4
  8. 64
  9. 512
  10. 4
  11. 216
  12. 18
  13. 27
  14. 27
  15. 9
  16. 1000
  17. 49
  18. 3
  19. 13
  20. 6
  21. 512
  22. 3375
  23. 64
  24. 18
  25. 25
  26. 216
  27. 16
  28. 64
  29. 9
  30. 6859
  31. 2
  32. 2197
  33. 24
  34. 64
  35. 19
  36. 7
  37. 17
  38. 2
  39. 5
  40. 12

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