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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 190 · 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 ∛8000? =
  2. 2.What is ∛13824? =
  3. 3.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  4. 4.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  5. 5.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  9. 9.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  10. 10.Which of these is a perfect cube? (a) 64 (b) 71 (c) 68
  11. 11.What is ∛512? =
  12. 12.What is 3³? =
  13. 13.What is ∛729? =
  14. 14.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  15. 15.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 2703 (b) 2197 (c) 2334
  17. 17.What is 15³? =
  18. 18.What is 11³? =
  19. 19.What is ∛3375? =
  20. 20.What is 13³? =
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  23. 23.Which of these is a perfect cube? (a) 1331 (b) 1547 (c) 1638
  24. 24.What is 12³? =
  25. 25.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  26. 26.What is 4³? =
  27. 27.What is ∛1000? =
  28. 28.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 3712 (b) 3643 (c) 3375
  31. 31.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  32. 32.What is 17³? =
  33. 33.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  34. 34.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  35. 35.What is ∛2197? =
  36. 36.What is 10³? =
  37. 37.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  38. 38.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.Which of these is a perfect cube? (a) 27 (b) 37 (c) 47
  40. 40.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 20
  2. 24
  3. 216
  4. 20
  5. 8
  6. 125
  7. 64
  8. 216
  9. 3
  10. 64
  11. 8
  12. 27
  13. 9
  14. 49
  15. 4
  16. 2197
  17. 3375
  18. 1331
  19. 15
  20. 2197
  21. 8
  22. 3
  23. 1331
  24. 1728
  25. 3
  26. 64
  27. 10
  28. 3
  29. 27
  30. 3375
  31. 12
  32. 4913
  33. 4
  34. 3
  35. 13
  36. 1000
  37. 9
  38. 64
  39. 27
  40. 8

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