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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 746 · 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 6³? =
  2. 2.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  3. 3.What is ∛12167? =
  4. 4.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  5. 5.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 146 (b) 197 (c) 125
  7. 7.What is 10³? =
  8. 8.Which of these is a perfect cube? (a) 364 (b) 343 (c) 434
  9. 9.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  11. 11.Which of these is a perfect cube? (a) 106 (b) 90 (c) 64
  12. 12.What is 20³? =
  13. 13.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  14. 14.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  15. 15.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  16. 16.What is 15³? =
  17. 17.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  18. 18.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  19. 19.What is 18³? =
  20. 20.What is 7³? =
  21. 21.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  22. 22.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  23. 23.What is ∛729? =
  24. 24.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  25. 25.What is ∛27? =
  26. 26.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.Which of these is a perfect cube? (a) 3043 (b) 3215 (c) 2744
  28. 28.What is ∛5832? =
  29. 29.What is ∛64? =
  30. 30.Which of these is a perfect cube? (a) 225 (b) 216 (c) 230
  31. 31.What is ∛216? =
  32. 32.What is 17³? =
  33. 33.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  34. 34.What is the smallest whole number by which 135 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  38. 38.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  39. 39.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?

Answer key

  1. 216
  2. 5
  3. 23
  4. 25
  5. 8
  6. 125
  7. 1000
  8. 343
  9. 125
  10. 3
  11. 64
  12. 8000
  13. 5
  14. 216
  15. 10
  16. 3375
  17. 8
  18. 4
  19. 5832
  20. 343
  21. 7
  22. 27
  23. 9
  24. 3
  25. 3
  26. 125
  27. 2744
  28. 18
  29. 4
  30. 216
  31. 6
  32. 4913
  33. 16
  34. 5
  35. 2
  36. 20
  37. 6
  38. 11
  39. 17
  40. 4

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