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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 923 · 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 cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  2. 2.What is 9³? =
  3. 3.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  4. 4.Which of these is a perfect cube? (a) 343 (b) 402 (c) 481
  5. 5.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  6. 6.What is ∛1331? =
  7. 7.What is ∛9261? =
  8. 8.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  10. 10.What is 18³? =
  11. 11.What is ∛3375? =
  12. 12.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  13. 13.What is ∛8? =
  14. 14.What is ∛125? =
  15. 15.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  16. 16.What is 15³? =
  17. 17.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is ∛1728? =
  19. 19.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  20. 20.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  21. 21.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  22. 22.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  23. 23.What is ∛4913? =
  24. 24.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  25. 25.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  26. 26.What is ∛2744? =
  27. 27.What is ∛12167? =
  28. 28.What is ∛216? =
  29. 29.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  30. 30.Which of these is a perfect cube? (a) 1000 (b) 1044 (c) 1206
  31. 31.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  32. 32.What is 4³? =
  33. 33.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  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 19³? =
  36. 36.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  37. 37.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  38. 38.Which of these is a perfect cube? (a) 301 (b) 282 (c) 216
  39. 39.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.What is the smallest whole number by which 4 must be divided to get a perfect cube?

Answer key

  1. 10
  2. 729
  3. 27
  4. 343
  5. 12
  6. 11
  7. 21
  8. 64
  9. 4
  10. 5832
  11. 15
  12. 9
  13. 2
  14. 5
  15. 14
  16. 3375
  17. 216
  18. 12
  19. 4
  20. 9
  21. 2
  22. 20
  23. 17
  24. 25
  25. 25
  26. 14
  27. 23
  28. 6
  29. 17
  30. 1000
  31. 11
  32. 64
  33. 19
  34. 8
  35. 6859
  36. 25
  37. 7
  38. 216
  39. 216
  40. 4

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