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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 120 · 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 6859 cubic cm. How long is each edge (in cm)?
  2. 2.What is ∛15625? =
  3. 3.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  4. 4.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  5. 5.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  6. 6.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  7. 7.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  8. 8.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  9. 9.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  10. 10.What is 15³? =
  11. 11.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  12. 12.What is ∛9261? =
  13. 13.What is 18³? =
  14. 14.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  15. 15.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  16. 16.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  17. 17.Which of these is a perfect cube? (a) 1873 (b) 1910 (c) 1728
  18. 18.Which of these is a perfect cube? (a) 3375 (b) 3880 (c) 3395
  19. 19.Which of these is a perfect cube? (a) 44 (b) 27 (c) 41
  20. 20.Which of these is a perfect cube? (a) 729 (b) 882 (c) 760
  21. 21.Which of these is a perfect cube? (a) 365 (b) 343 (c) 453
  22. 22.What is 4³? =
  23. 23.What is ∛125? =
  24. 24.Which of these is a perfect cube? (a) 1586 (b) 1517 (c) 1331
  25. 25.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  26. 26.What is 9³? =
  27. 27.What is 10³? =
  28. 28.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  29. 29.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  30. 30.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  31. 31.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  32. 32.What is ∛2744? =
  33. 33.What is ∛8000? =
  34. 34.Which of these is a perfect cube? (a) 2620 (b) 2275 (c) 2197
  35. 35.Which of these is a perfect cube? (a) 64 (b) 97 (c) 76
  36. 36.What is ∛729? =
  37. 37.What is ∛1728? =
  38. 38.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  39. 39.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  40. 40.What is the smallest whole number by which 432 must be divided to get a perfect cube?

Answer key

  1. 19
  2. 25
  3. 5
  4. 27
  5. 2
  6. 7
  7. 4
  8. 3
  9. 3
  10. 3375
  11. 49
  12. 21
  13. 5832
  14. 7
  15. 2
  16. 8
  17. 1728
  18. 3375
  19. 27
  20. 729
  21. 343
  22. 64
  23. 5
  24. 1331
  25. 9
  26. 729
  27. 1000
  28. 17
  29. 15
  30. 64
  31. 11
  32. 14
  33. 20
  34. 2197
  35. 64
  36. 9
  37. 12
  38. 13
  39. 4
  40. 2

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