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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 112 · 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 big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 259 (b) 216 (c) 223
  3. 3.Which of these is a perfect cube? (a) 93 (b) 64 (c) 71
  4. 4.What is ∛512? =
  5. 5.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  6. 6.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  7. 7.What is ∛9261? =
  8. 8.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  9. 9.Which of these is a perfect cube? (a) 1507 (b) 1331 (c) 1563
  10. 10.What is ∛13824? =
  11. 11.Which of these is a perfect cube? (a) 2919 (b) 2744 (c) 3105
  12. 12.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  13. 13.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  15. 15.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  16. 16.What is ∛216? =
  17. 17.What is ∛2744? =
  18. 18.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  19. 19.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  20. 20.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  21. 21.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  22. 22.What is 8³? =
  23. 23.What is 13³? =
  24. 24.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  25. 25.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  26. 26.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  27. 27.What is 18³? =
  28. 28.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  29. 29.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  30. 30.What is 2³? =
  31. 31.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  32. 32.Which of these is a perfect cube? (a) 1221 (b) 1142 (c) 1000
  33. 33.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  34. 34.What is 5³? =
  35. 35.What is 4³? =
  36. 36.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  37. 37.Which of these is a perfect cube? (a) 1728 (b) 1913 (c) 1905
  38. 38.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  39. 39.What is 7³? =
  40. 40.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?

Answer key

  1. 125
  2. 216
  3. 64
  4. 8
  5. 49
  6. 8
  7. 21
  8. 17
  9. 1331
  10. 24
  11. 2744
  12. 64
  13. 64
  14. 5
  15. 4
  16. 6
  17. 14
  18. 15
  19. 9
  20. 18
  21. 25
  22. 512
  23. 2197
  24. 3
  25. 7
  26. 9
  27. 5832
  28. 4
  29. 25
  30. 8
  31. 8
  32. 1000
  33. 25
  34. 125
  35. 64
  36. 9
  37. 1728
  38. 7
  39. 343
  40. 27

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