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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 495 · 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 ∛9261? =
  2. 2.What is 15³? =
  3. 3.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  4. 4.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  5. 5.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 2342 (b) 2526 (c) 2197
  7. 7.Which of these is a perfect cube? (a) 27 (b) 43 (c) 44
  8. 8.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  9. 9.What is ∛5832? =
  10. 10.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  11. 11.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  12. 12.What is 8³? =
  13. 13.What is 4³? =
  14. 14.Which of these is a perfect cube? (a) 64 (b) 86 (c) 77
  15. 15.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  16. 16.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  17. 17.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  18. 18.Which of these is a perfect cube? (a) 524 (b) 512 (c) 596
  19. 19.What is ∛729? =
  20. 20.Which of these is a perfect cube? (a) 3375 (b) 3670 (c) 3641
  21. 21.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  22. 22.What is ∛343? =
  23. 23.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  24. 24.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  25. 25.What is 9³? =
  26. 26.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  27. 27.What is 2³? =
  28. 28.Which of these is a perfect cube? (a) 1760 (b) 1942 (c) 1728
  29. 29.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is ∛216? =
  32. 32.What is ∛8? =
  33. 33.What is ∛125? =
  34. 34.What is ∛64? =
  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.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  37. 37.What is ∛13824? =
  38. 38.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  40. 40.Which of these is a perfect cube? (a) 1296 (b) 1000 (c) 1011

Answer key

  1. 21
  2. 3375
  3. 2
  4. 125
  5. 8
  6. 2197
  7. 27
  8. 5
  9. 18
  10. 25
  11. 3
  12. 512
  13. 64
  14. 64
  15. 18
  16. 216
  17. 13
  18. 512
  19. 9
  20. 3375
  21. 3
  22. 7
  23. 12
  24. 25
  25. 729
  26. 4
  27. 8
  28. 1728
  29. 125
  30. 64
  31. 6
  32. 2
  33. 5
  34. 4
  35. 8
  36. 27
  37. 24
  38. 216
  39. 8
  40. 1000

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