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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 385 · 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 ∛64? =
  2. 2.Which of these is a perfect cube? (a) 1036 (b) 1000 (c) 1143
  3. 3.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  4. 4.What is ∛27? =
  5. 5.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 1996 (b) 2036 (c) 1728
  7. 7.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  8. 8.What is 3³? =
  9. 9.Which of these is a perfect cube? (a) 182 (b) 145 (c) 125
  10. 10.What is 16³? =
  11. 11.What is 20³? =
  12. 12.Which of these is a perfect cube? (a) 27 (b) 39 (c) 42
  13. 13.What is 19³? =
  14. 14.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is 17³? =
  16. 16.What is ∛125? =
  17. 17.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  20. 20.Which of these is a perfect cube? (a) 555 (b) 512 (c) 560
  21. 21.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is 9³? =
  23. 23.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 410 (b) 486 (c) 343
  25. 25.Which of these is a perfect cube? (a) 2819 (b) 2744 (c) 3243
  26. 26.What is 14³? =
  27. 27.Which of these is a perfect cube? (a) 294 (b) 240 (c) 216
  28. 28.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  29. 29.What is 13³? =
  30. 30.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  31. 31.What is 4³? =
  32. 32.What is ∛5832? =
  33. 33.What is ∛1728? =
  34. 34.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  35. 35.What is ∛13824? =
  36. 36.What is 10³? =
  37. 37.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  38. 38.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  40. 40.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?

Answer key

  1. 4
  2. 1000
  3. 9
  4. 3
  5. 64
  6. 1728
  7. 49
  8. 27
  9. 125
  10. 4096
  11. 8000
  12. 27
  13. 6859
  14. 27
  15. 4913
  16. 5
  17. 8
  18. 64
  19. 17
  20. 512
  21. 125
  22. 729
  23. 25
  24. 343
  25. 2744
  26. 2744
  27. 216
  28. 49
  29. 2197
  30. 5
  31. 64
  32. 18
  33. 12
  34. 2
  35. 24
  36. 1000
  37. 216
  38. 64
  39. 25
  40. 64

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