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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 849 · 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) 99 (b) 97 (c) 64
  2. 2.Which of these is a perfect cube? (a) 447 (b) 343 (c) 378
  3. 3.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  4. 4.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  5. 5.What is 3³? =
  6. 6.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  7. 7.What is 15³? =
  8. 8.Which of these is a perfect cube? (a) 614 (b) 512 (c) 654
  9. 9.What is 14³? =
  10. 10.Which of these is a perfect cube? (a) 843 (b) 893 (c) 729
  11. 11.Which of these is a perfect cube? (a) 2811 (b) 2744 (c) 3328
  12. 12.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  13. 13.What is ∛729? =
  14. 14.Which of these is a perfect cube? (a) 125 (b) 148 (c) 198
  15. 15.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.What is 4³? =
  17. 17.Which of these is a perfect cube? (a) 2047 (b) 1926 (c) 1728
  18. 18.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  20. 20.Which of these is a perfect cube? (a) 3375 (b) 3454 (c) 3861
  21. 21.What is ∛5832? =
  22. 22.What is ∛1728? =
  23. 23.What is 13³? =
  24. 24.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  25. 25.What is ∛4096? =
  26. 26.What is 19³? =
  27. 27.What is 18³? =
  28. 28.Which of these is a perfect cube? (a) 216 (b) 248 (c) 265
  29. 29.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.What is 17³? =
  31. 31.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  32. 32.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  33. 33.Which of these is a perfect cube? (a) 27 (b) 48 (c) 43
  34. 34.What is ∛9261? =
  35. 35.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  37. 37.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  38. 38.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  39. 39.What is 8³? =
  40. 40.What is ∛512? =

Answer key

  1. 64
  2. 343
  3. 8
  4. 3
  5. 27
  6. 9
  7. 3375
  8. 512
  9. 2744
  10. 729
  11. 2744
  12. 16
  13. 9
  14. 125
  15. 216
  16. 64
  17. 1728
  18. 125
  19. 5
  20. 3375
  21. 18
  22. 12
  23. 2197
  24. 9
  25. 16
  26. 6859
  27. 5832
  28. 216
  29. 27
  30. 4913
  31. 2
  32. 20
  33. 27
  34. 21
  35. 8
  36. 3
  37. 49
  38. 19
  39. 512
  40. 8

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