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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 980 · 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) 34 (b) 50 (c) 27
  2. 2.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.What is ∛64? =
  4. 4.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  5. 5.What is 11³? =
  6. 6.What is ∛13824? =
  7. 7.Which of these is a perfect cube? (a) 78 (b) 64 (c) 83
  8. 8.What is ∛216? =
  9. 9.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  10. 10.What is 5³? =
  11. 11.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  14. 14.Which of these is a perfect cube? (a) 2824 (b) 2906 (c) 2744
  15. 15.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  16. 16.What is ∛4096? =
  17. 17.What is 17³? =
  18. 18.What is 18³? =
  19. 19.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  20. 20.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  21. 21.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  22. 22.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  23. 23.What is 7³? =
  24. 24.Which of these is a perfect cube? (a) 216 (b) 228 (c) 288
  25. 25.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  26. 26.What is ∛8? =
  27. 27.What is 9³? =
  28. 28.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  29. 29.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  31. 31.Which of these is a perfect cube? (a) 3714 (b) 3708 (c) 3375
  32. 32.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  33. 33.What is 3³? =
  34. 34.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  36. 36.What is ∛1331? =
  37. 37.What is 19³? =
  38. 38.What is ∛2197? =
  39. 39.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  40. 40.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?

Answer key

  1. 27
  2. 216
  3. 4
  4. 2
  5. 1331
  6. 24
  7. 64
  8. 6
  9. 4
  10. 125
  11. 125
  12. 20
  13. 12
  14. 2744
  15. 8
  16. 16
  17. 4913
  18. 5832
  19. 5
  20. 15
  21. 25
  22. 11
  23. 343
  24. 216
  25. 25
  26. 2
  27. 729
  28. 5
  29. 216
  30. 9
  31. 3375
  32. 2
  33. 27
  34. 8
  35. 14
  36. 11
  37. 6859
  38. 13
  39. 27
  40. 25

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