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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 624 · 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 16³? =
  2. 2.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.Which of these is a perfect cube? (a) 400 (b) 343 (c) 473
  4. 4.Which of these is a perfect cube? (a) 64 (b) 112 (c) 111
  5. 5.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  6. 6.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  7. 7.What is ∛5832? =
  8. 8.What is ∛125? =
  9. 9.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  10. 10.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  11. 11.What is ∛3375? =
  12. 12.What is 3³? =
  13. 13.What is 4³? =
  14. 14.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  16. 16.What is ∛8? =
  17. 17.What is 7³? =
  18. 18.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.What is ∛512? =
  20. 20.What is ∛6859? =
  21. 21.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  22. 22.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  23. 23.What is 12³? =
  24. 24.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  25. 25.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 2197 (b) 2355 (c) 2595
  27. 27.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  30. 30.What is ∛4913? =
  31. 31.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  32. 32.What is 19³? =
  33. 33.What is ∛9261? =
  34. 34.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  35. 35.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  36. 36.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  37. 37.What is 18³? =
  38. 38.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  39. 39.What is 17³? =
  40. 40.What is 11³? =

Answer key

  1. 4096
  2. 8
  3. 343
  4. 64
  5. 4
  6. 27
  7. 18
  8. 5
  9. 7
  10. 49
  11. 15
  12. 27
  13. 64
  14. 64
  15. 9
  16. 2
  17. 343
  18. 216
  19. 8
  20. 19
  21. 19
  22. 13
  23. 1728
  24. 9
  25. 4
  26. 2197
  27. 8
  28. 64
  29. 3
  30. 17
  31. 10
  32. 6859
  33. 21
  34. 5
  35. 15
  36. 14
  37. 5832
  38. 4
  39. 4913
  40. 1331

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