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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 864 · 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 ∛15625? =
  2. 2.Which of these is a perfect cube? (a) 1728 (b) 2135 (c) 1875
  3. 3.What is 20³? =
  4. 4.What is 18³? =
  5. 5.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.What is ∛27? =
  7. 7.Which of these is a perfect cube? (a) 27 (b) 48 (c) 36
  8. 8.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  10. 10.What is ∛512? =
  11. 11.What is ∛12167? =
  12. 12.What is ∛2197? =
  13. 13.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  14. 14.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  15. 15.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  16. 16.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  17. 17.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  20. 20.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  21. 21.What is 17³? =
  22. 22.What is 15³? =
  23. 23.What is ∛729? =
  24. 24.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 3186 (b) 3276 (c) 2744
  27. 27.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.What is ∛1728? =
  29. 29.What is 14³? =
  30. 30.Which of these is a perfect cube? (a) 133 (b) 125 (c) 159
  31. 31.What is 5³? =
  32. 32.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  33. 33.What is ∛125? =
  34. 34.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  35. 35.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.What is 8³? =
  37. 37.What is ∛343? =
  38. 38.What is 2³? =
  39. 39.What is 9³? =
  40. 40.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?

Answer key

  1. 25
  2. 1728
  3. 8000
  4. 5832
  5. 216
  6. 3
  7. 27
  8. 125
  9. 3
  10. 8
  11. 23
  12. 13
  13. 16
  14. 8
  15. 7
  16. 11
  17. 216
  18. 125
  19. 49
  20. 49
  21. 4913
  22. 3375
  23. 9
  24. 27
  25. 49
  26. 2744
  27. 8
  28. 12
  29. 2744
  30. 125
  31. 125
  32. 9
  33. 5
  34. 27
  35. 125
  36. 512
  37. 7
  38. 8
  39. 729
  40. 216

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