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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 280 · 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 cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  2. 2.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.What is 19³? =
  4. 4.Which of these is a perfect cube? (a) 2991 (b) 2756 (c) 2744
  5. 5.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  6. 6.Which of these is a perfect cube? (a) 1804 (b) 1760 (c) 1728
  7. 7.What is ∛9261? =
  8. 8.What is 3³? =
  9. 9.What is ∛512? =
  10. 10.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  11. 11.What is 13³? =
  12. 12.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  13. 13.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  15. 15.What is 2³? =
  16. 16.Which of these is a perfect cube? (a) 167 (b) 149 (c) 125
  17. 17.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  18. 18.Which of these is a perfect cube? (a) 729 (b) 834 (c) 778
  19. 19.What is 6³? =
  20. 20.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  21. 21.What is 17³? =
  22. 22.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  23. 23.What is ∛27? =
  24. 24.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  25. 25.What is 10³? =
  26. 26.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  27. 27.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  28. 28.What is ∛2744? =
  29. 29.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  30. 30.What is ∛1728? =
  31. 31.What is 20³? =
  32. 32.What is ∛12167? =
  33. 33.What is 18³? =
  34. 34.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  35. 35.Which of these is a perfect cube? (a) 1331 (b) 1630 (c) 1579
  36. 36.What is 12³? =
  37. 37.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  38. 38.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  39. 39.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  40. 40.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 19
  2. 216
  3. 6859
  4. 2744
  5. 5
  6. 1728
  7. 21
  8. 27
  9. 8
  10. 5
  11. 2197
  12. 10
  13. 27
  14. 3
  15. 8
  16. 125
  17. 20
  18. 729
  19. 216
  20. 125
  21. 4913
  22. 2
  23. 3
  24. 9
  25. 1000
  26. 216
  27. 7
  28. 14
  29. 4
  30. 12
  31. 8000
  32. 23
  33. 5832
  34. 27
  35. 1331
  36. 1728
  37. 49
  38. 27
  39. 9
  40. 216

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