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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 148 · 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.Which of these is a perfect cube? (a) 216 (b) 218 (c) 219
  2. 2.Which of these is a perfect cube? (a) 2744 (b) 2996 (c) 2761
  3. 3.Which of these is a perfect cube? (a) 1331 (b) 1401 (c) 1487
  4. 4.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  5. 5.What is ∛8000? =
  6. 6.What is ∛729? =
  7. 7.What is ∛1331? =
  8. 8.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  10. 10.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is 8³? =
  12. 12.What is ∛5832? =
  13. 13.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.What is 13³? =
  15. 15.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 43 (b) 27 (c) 45
  17. 17.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.What is ∛8? =
  19. 19.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is 7³? =
  21. 21.Which of these is a perfect cube? (a) 2633 (b) 2197 (c) 2550
  22. 22.Which of these is a perfect cube? (a) 64 (b) 76 (c) 90
  23. 23.What is 14³? =
  24. 24.What is ∛6859? =
  25. 25.What is 15³? =
  26. 26.Which of these is a perfect cube? (a) 729 (b) 969 (c) 943
  27. 27.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛1728? =
  30. 30.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  31. 31.What is 4³? =
  32. 32.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  33. 33.What is 5³? =
  34. 34.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.What is ∛15625? =
  36. 36.What is ∛512? =
  37. 37.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  38. 38.What is ∛64? =
  39. 39.What is ∛4913? =
  40. 40.What is the smallest whole number by which 1323 must be divided to get a perfect cube?

Answer key

  1. 216
  2. 2744
  3. 1331
  4. 16
  5. 20
  6. 9
  7. 11
  8. 8
  9. 9
  10. 64
  11. 512
  12. 18
  13. 64
  14. 2197
  15. 4
  16. 27
  17. 8
  18. 2
  19. 27
  20. 343
  21. 2197
  22. 64
  23. 2744
  24. 19
  25. 3375
  26. 729
  27. 125
  28. 12
  29. 12
  30. 216
  31. 64
  32. 20
  33. 125
  34. 8
  35. 25
  36. 8
  37. 2
  38. 4
  39. 17
  40. 49

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