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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 520 · 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 ∛13824? =
  2. 2.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  5. 5.Which of these is a perfect cube? (a) 1166 (b) 1132 (c) 1000
  6. 6.What is ∛10648? =
  7. 7.Which of these is a perfect cube? (a) 132 (b) 125 (c) 153
  8. 8.What is ∛1331? =
  9. 9.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  10. 10.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is ∛8? =
  12. 12.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  13. 13.What is ∛27? =
  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 243 must be multiplied to get a perfect cube?
  16. 16.What is 2³? =
  17. 17.Which of these is a perfect cube? (a) 363 (b) 343 (c) 414
  18. 18.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  19. 19.What is ∛1728? =
  20. 20.What is 6³? =
  21. 21.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛6859? =
  23. 23.Which of these is a perfect cube? (a) 1331 (b) 1694 (c) 1661
  24. 24.What is ∛729? =
  25. 25.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  26. 26.What is 5³? =
  27. 27.Which of these is a perfect cube? (a) 27 (b) 33 (c) 34
  28. 28.What is 9³? =
  29. 29.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  30. 30.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  31. 31.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  32. 32.What is ∛2744? =
  33. 33.What is ∛512? =
  34. 34.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  35. 35.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.Which of these is a perfect cube? (a) 216 (b) 227 (c) 257
  37. 37.What is 4³? =
  38. 38.What is ∛1000? =
  39. 39.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  40. 40.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?

Answer key

  1. 24
  2. 27
  3. 27
  4. 7
  5. 1000
  6. 22
  7. 125
  8. 11
  9. 7
  10. 216
  11. 2
  12. 4
  13. 3
  14. 64
  15. 3
  16. 8
  17. 343
  18. 8
  19. 12
  20. 216
  21. 9
  22. 19
  23. 1331
  24. 9
  25. 3
  26. 125
  27. 27
  28. 729
  29. 4
  30. 12
  31. 7
  32. 14
  33. 8
  34. 2
  35. 8
  36. 216
  37. 64
  38. 10
  39. 216
  40. 49

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