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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 709 · 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 13³? =
  2. 2.What is ∛125? =
  3. 3.Which of these is a perfect cube? (a) 461 (b) 343 (c) 394
  4. 4.Which of these is a perfect cube? (a) 1395 (b) 1390 (c) 1331
  5. 5.What is 17³? =
  6. 6.What is 4³? =
  7. 7.What is ∛6859? =
  8. 8.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  9. 9.What is 3³? =
  10. 10.What is ∛512? =
  11. 11.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  12. 12.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  13. 13.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  14. 14.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  15. 15.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  17. 17.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  19. 19.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  20. 20.What is 14³? =
  21. 21.What is ∛8? =
  22. 22.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  23. 23.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  24. 24.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  25. 25.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 1225 (b) 1041 (c) 1000
  27. 27.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  28. 28.What is ∛12167? =
  29. 29.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  30. 30.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  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.What is the smallest whole number by which 135 must be divided to get a perfect cube?
  33. 33.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.Which of these is a perfect cube? (a) 272 (b) 245 (c) 216
  35. 35.What is ∛8000? =
  36. 36.Which of these is a perfect cube? (a) 539 (b) 670 (c) 512
  37. 37.What is ∛4096? =
  38. 38.Which of these is a perfect cube? (a) 1728 (b) 1791 (c) 2035
  39. 39.What is ∛3375? =
  40. 40.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?

Answer key

  1. 2197
  2. 5
  3. 343
  4. 1331
  5. 4913
  6. 64
  7. 19
  8. 3
  9. 27
  10. 8
  11. 3
  12. 7
  13. 4
  14. 8
  15. 216
  16. 125
  17. 125
  18. 49
  19. 14
  20. 2744
  21. 2
  22. 3
  23. 25
  24. 15
  25. 5
  26. 1000
  27. 2
  28. 23
  29. 3
  30. 8
  31. 8
  32. 5
  33. 64
  34. 216
  35. 20
  36. 512
  37. 16
  38. 1728
  39. 15
  40. 5

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