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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 642 · 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 1080 must be divided to get a perfect cube?
  2. 2.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  3. 3.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  5. 5.What is 17³? =
  6. 6.What is 6³? =
  7. 7.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  8. 8.What is ∛4913? =
  9. 9.Which of these is a perfect cube? (a) 65 (b) 93 (c) 64
  10. 10.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  11. 11.What is ∛5832? =
  12. 12.What is 5³? =
  13. 13.What is 14³? =
  14. 14.What is 7³? =
  15. 15.What is ∛15625? =
  16. 16.Which of these is a perfect cube? (a) 38 (b) 31 (c) 27
  17. 17.A big cube of edge 2 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 192 must be multiplied to get a perfect cube?
  19. 19.What is ∛729? =
  20. 20.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  21. 21.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is ∛6859? =
  23. 23.Which of these is a perfect cube? (a) 2614 (b) 2552 (c) 2197
  24. 24.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  25. 25.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  26. 26.Which of these is a perfect cube? (a) 1758 (b) 1774 (c) 1728
  27. 27.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  28. 28.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  29. 29.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  30. 30.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  31. 31.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  32. 32.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  33. 33.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  34. 34.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  35. 35.Which of these is a perfect cube? (a) 947 (b) 729 (c) 772
  36. 36.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  38. 38.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  39. 39.What is 11³? =
  40. 40.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?

Answer key

  1. 5
  2. 64
  3. 8
  4. 5
  5. 4913
  6. 216
  7. 14
  8. 17
  9. 64
  10. 4
  11. 18
  12. 125
  13. 2744
  14. 343
  15. 25
  16. 27
  17. 8
  18. 9
  19. 9
  20. 5
  21. 125
  22. 19
  23. 2197
  24. 216
  25. 16
  26. 1728
  27. 3
  28. 4
  29. 8
  30. 64
  31. 125
  32. 11
  33. 17
  34. 6
  35. 729
  36. 216
  37. 49
  38. 8
  39. 1331
  40. 25

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