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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 259 · 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 ∛216? =
  2. 2.What is ∛5832? =
  3. 3.What is ∛2197? =
  4. 4.What is 8³? =
  5. 5.Which of these is a perfect cube? (a) 343 (b) 482 (c) 458
  6. 6.What is 3³? =
  7. 7.What is ∛2744? =
  8. 8.Which of these is a perfect cube? (a) 109 (b) 64 (c) 97
  9. 9.Which of these is a perfect cube? (a) 4044 (b) 3409 (c) 3375
  10. 10.What is 2³? =
  11. 11.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  12. 12.Which of these is a perfect cube? (a) 729 (b) 851 (c) 885
  13. 13.Which of these is a perfect cube? (a) 125 (b) 161 (c) 137
  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.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  16. 16.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  17. 17.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  18. 18.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  20. 20.What is ∛1728? =
  21. 21.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  22. 22.Which of these is a perfect cube? (a) 1728 (b) 1769 (c) 1734
  23. 23.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  26. 26.What is ∛512? =
  27. 27.What is 9³? =
  28. 28.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  29. 29.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  30. 30.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  32. 32.What is 15³? =
  33. 33.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  34. 34.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  35. 35.What is ∛27? =
  36. 36.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  37. 37.What is 14³? =
  38. 38.What is 5³? =
  39. 39.What is ∛125? =
  40. 40.What is ∛15625? =

Answer key

  1. 6
  2. 18
  3. 13
  4. 512
  5. 343
  6. 27
  7. 14
  8. 64
  9. 3375
  10. 8
  11. 49
  12. 729
  13. 125
  14. 8
  15. 5
  16. 4
  17. 7
  18. 27
  19. 49
  20. 12
  21. 8
  22. 1728
  23. 8
  24. 64
  25. 5
  26. 8
  27. 729
  28. 5
  29. 5
  30. 27
  31. 2
  32. 3375
  33. 27
  34. 9
  35. 3
  36. 20
  37. 2744
  38. 125
  39. 5
  40. 25

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