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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 903 · 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 ∛216? =
  2. 2.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  3. 3.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  4. 4.What is ∛2197? =
  5. 5.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  7. 7.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  8. 8.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.What is 6³? =
  10. 10.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  12. 12.What is 8³? =
  13. 13.Which of these is a perfect cube? (a) 190 (b) 125 (c) 143
  14. 14.Which of these is a perfect cube? (a) 1581 (b) 1331 (c) 1561
  15. 15.Which of these is a perfect cube? (a) 571 (b) 581 (c) 512
  16. 16.What is ∛2744? =
  17. 17.Which of these is a perfect cube? (a) 3093 (b) 2744 (c) 2822
  18. 18.What is ∛13824? =
  19. 19.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  20. 20.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  21. 21.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  22. 22.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  23. 23.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  24. 24.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  26. 26.What is 12³? =
  27. 27.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  28. 28.Which of these is a perfect cube? (a) 356 (b) 364 (c) 343
  29. 29.What is ∛8000? =
  30. 30.What is ∛4096? =
  31. 31.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  32. 32.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  33. 33.What is ∛6859? =
  34. 34.What is 19³? =
  35. 35.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  36. 36.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  37. 37.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  38. 38.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.Which of these is a perfect cube? (a) 54 (b) 49 (c) 27
  40. 40.What is 7³? =

Answer key

  1. 6
  2. 25
  3. 7
  4. 13
  5. 125
  6. 4
  7. 49
  8. 8
  9. 216
  10. 27
  11. 16
  12. 512
  13. 125
  14. 1331
  15. 512
  16. 14
  17. 2744
  18. 24
  19. 125
  20. 216
  21. 3
  22. 12
  23. 5
  24. 64
  25. 216
  26. 1728
  27. 2
  28. 343
  29. 20
  30. 16
  31. 9
  32. 2
  33. 19
  34. 6859
  35. 18
  36. 25
  37. 3
  38. 8
  39. 27
  40. 343

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