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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 730 · 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 big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 1948 (b) 1728 (c) 1982
  3. 3.What is 7³? =
  4. 4.Which of these is a perfect cube? (a) 2668 (b) 2394 (c) 2197
  5. 5.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  6. 6.What is 20³? =
  7. 7.Which of these is a perfect cube? (a) 74 (b) 91 (c) 64
  8. 8.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  9. 9.What is ∛12167? =
  10. 10.Which of these is a perfect cube? (a) 792 (b) 874 (c) 729
  11. 11.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  12. 12.Which of these is a perfect cube? (a) 132 (b) 165 (c) 125
  13. 13.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  14. 14.What is 11³? =
  15. 15.What is 6³? =
  16. 16.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  17. 17.What is 2³? =
  18. 18.What is 9³? =
  19. 19.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.Which of these is a perfect cube? (a) 39 (b) 49 (c) 27
  21. 21.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  22. 22.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  23. 23.What is ∛10648? =
  24. 24.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  25. 25.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  26. 26.What is ∛8000? =
  27. 27.What is ∛4096? =
  28. 28.What is ∛2744? =
  29. 29.What is 12³? =
  30. 30.What is ∛27? =
  31. 31.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  32. 32.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  33. 33.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 343 (b) 413 (c) 425
  36. 36.What is 4³? =
  37. 37.Which of these is a perfect cube? (a) 216 (b) 296 (c) 263
  38. 38.What is 18³? =
  39. 39.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?

Answer key

  1. 64
  2. 1728
  3. 343
  4. 2197
  5. 6
  6. 8000
  7. 64
  8. 49
  9. 23
  10. 729
  11. 16
  12. 125
  13. 10
  14. 1331
  15. 216
  16. 27
  17. 8
  18. 729
  19. 125
  20. 27
  21. 4
  22. 12
  23. 22
  24. 9
  25. 3
  26. 20
  27. 16
  28. 14
  29. 1728
  30. 3
  31. 2
  32. 7
  33. 216
  34. 9
  35. 343
  36. 64
  37. 216
  38. 5832
  39. 4
  40. 2

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