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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 317 · 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 7 must be divided to get a perfect cube?
  2. 2.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  3. 3.What is ∛1000? =
  4. 4.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  5. 5.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  6. 6.What is ∛2744? =
  7. 7.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  8. 8.What is 17³? =
  9. 9.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.What is 9³? =
  11. 11.What is 18³? =
  12. 12.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  13. 13.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  14. 14.What is 12³? =
  15. 15.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  17. 17.What is 13³? =
  18. 18.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  19. 19.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  20. 20.What is 19³? =
  21. 21.What is ∛3375? =
  22. 22.What is ∛512? =
  23. 23.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  24. 24.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  25. 25.Which of these is a perfect cube? (a) 222 (b) 216 (c) 240
  26. 26.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  27. 27.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  29. 29.What is 6³? =
  30. 30.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  31. 31.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  32. 32.What is 16³? =
  33. 33.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  34. 34.What is 8³? =
  35. 35.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  37. 37.Which of these is a perfect cube? (a) 1405 (b) 1331 (c) 1552
  38. 38.What is 10³? =
  39. 39.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  40. 40.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 7
  2. 8
  3. 10
  4. 216
  5. 12
  6. 14
  7. 2
  8. 4913
  9. 216
  10. 729
  11. 5832
  12. 3
  13. 4
  14. 1728
  15. 125
  16. 8
  17. 2197
  18. 7
  19. 27
  20. 6859
  21. 15
  22. 8
  23. 2
  24. 7
  25. 216
  26. 15
  27. 64
  28. 11
  29. 216
  30. 216
  31. 10
  32. 4096
  33. 25
  34. 512
  35. 64
  36. 25
  37. 1331
  38. 1000
  39. 3
  40. 27

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