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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 931 · 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.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  3. 3.What is ∛6859? =
  4. 4.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  5. 5.What is 4³? =
  6. 6.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  7. 7.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  8. 8.What is 14³? =
  9. 9.What is ∛216? =
  10. 10.What is ∛4913? =
  11. 11.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  12. 12.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  14. 14.What is 2³? =
  15. 15.Which of these is a perfect cube? (a) 524 (b) 621 (c) 512
  16. 16.What is ∛512? =
  17. 17.What is 6³? =
  18. 18.What is 3³? =
  19. 19.What is ∛5832? =
  20. 20.Which of these is a perfect cube? (a) 46 (b) 27 (c) 34
  21. 21.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  22. 22.Which of these is a perfect cube? (a) 173 (b) 125 (c) 155
  23. 23.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  24. 24.What is 10³? =
  25. 25.What is 12³? =
  26. 26.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.What is ∛729? =
  29. 29.Which of these is a perfect cube? (a) 64 (b) 91 (c) 89
  30. 30.What is ∛27? =
  31. 31.What is 13³? =
  32. 32.What is 18³? =
  33. 33.What is ∛343? =
  34. 34.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  35. 35.What is ∛12167? =
  36. 36.What is ∛15625? =
  37. 37.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  38. 38.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  39. 39.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?

Answer key

  1. 64
  2. 2
  3. 19
  4. 2
  5. 64
  6. 11
  7. 3
  8. 2744
  9. 6
  10. 17
  11. 17
  12. 20
  13. 16
  14. 8
  15. 512
  16. 8
  17. 216
  18. 27
  19. 18
  20. 27
  21. 3
  22. 125
  23. 2
  24. 1000
  25. 1728
  26. 27
  27. 27
  28. 9
  29. 64
  30. 3
  31. 2197
  32. 5832
  33. 7
  34. 9
  35. 23
  36. 25
  37. 8
  38. 4
  39. 13
  40. 49

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