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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 922 · 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 the smallest whole number by which 72 must be multiplied to get a perfect cube?
  2. 2.What is 7³? =
  3. 3.What is 3³? =
  4. 4.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  5. 5.What is 18³? =
  6. 6.Which of these is a perfect cube? (a) 2759 (b) 2744 (c) 2847
  7. 7.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.Which of these is a perfect cube? (a) 28 (b) 27 (c) 31
  9. 9.What is ∛13824? =
  10. 10.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  11. 11.What is 2³? =
  12. 12.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  14. 14.What is 13³? =
  15. 15.Which of these is a perfect cube? (a) 2682 (b) 2197 (c) 2532
  16. 16.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  17. 17.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  18. 18.What is 15³? =
  19. 19.What is 5³? =
  20. 20.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  21. 21.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  22. 22.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  23. 23.What is ∛8? =
  24. 24.What is 12³? =
  25. 25.What is ∛216? =
  26. 26.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  27. 27.What is ∛125? =
  28. 28.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  29. 29.What is ∛12167? =
  30. 30.What is ∛8000? =
  31. 31.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  32. 32.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  33. 33.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  35. 35.Which of these is a perfect cube? (a) 102 (b) 78 (c) 64
  36. 36.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  37. 37.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  38. 38.Which of these is a perfect cube? (a) 1236 (b) 1125 (c) 1000
  39. 39.Which of these is a perfect cube? (a) 729 (b) 949 (c) 896
  40. 40.What is ∛2744? =

Answer key

  1. 3
  2. 343
  3. 27
  4. 3
  5. 5832
  6. 2744
  7. 216
  8. 27
  9. 24
  10. 9
  11. 8
  12. 27
  13. 49
  14. 2197
  15. 2197
  16. 7
  17. 11
  18. 3375
  19. 125
  20. 5
  21. 15
  22. 3
  23. 2
  24. 1728
  25. 6
  26. 9
  27. 5
  28. 25
  29. 23
  30. 20
  31. 216
  32. 4
  33. 8
  34. 64
  35. 64
  36. 4
  37. 20
  38. 1000
  39. 729
  40. 14

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