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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 115 · 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 cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  2. 2.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  3. 3.What is ∛27? =
  4. 4.What is ∛1331? =
  5. 5.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  6. 6.What is 4³? =
  7. 7.What is 13³? =
  8. 8.What is ∛5832? =
  9. 9.What is ∛216? =
  10. 10.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is 18³? =
  12. 12.What is 7³? =
  13. 13.What is ∛6859? =
  14. 14.What is 2³? =
  15. 15.Which of these is a perfect cube? (a) 1448 (b) 1420 (c) 1331
  16. 16.Which of these is a perfect cube? (a) 531 (b) 659 (c) 512
  17. 17.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  18. 18.What is ∛1728? =
  19. 19.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  21. 21.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  22. 22.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  23. 23.Which of these is a perfect cube? (a) 862 (b) 962 (c) 729
  24. 24.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  25. 25.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  26. 26.What is ∛729? =
  27. 27.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  28. 28.Which of these is a perfect cube? (a) 302 (b) 216 (c) 279
  29. 29.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  30. 30.Which of these is a perfect cube? (a) 1000 (b) 1041 (c) 1226
  31. 31.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  32. 32.What is ∛8? =
  33. 33.What is 19³? =
  34. 34.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  35. 35.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  36. 36.What is 20³? =
  37. 37.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  38. 38.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  39. 39.What is ∛8000? =
  40. 40.Which of these is a perfect cube? (a) 3046 (b) 3314 (c) 2744

Answer key

  1. 19
  2. 9
  3. 3
  4. 11
  5. 14
  6. 64
  7. 2197
  8. 18
  9. 6
  10. 64
  11. 5832
  12. 343
  13. 19
  14. 8
  15. 1331
  16. 512
  17. 27
  18. 12
  19. 216
  20. 4
  21. 25
  22. 8
  23. 729
  24. 3
  25. 18
  26. 9
  27. 7
  28. 216
  29. 2
  30. 1000
  31. 9
  32. 2
  33. 6859
  34. 13
  35. 4
  36. 8000
  37. 3
  38. 125
  39. 20
  40. 2744

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