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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 694 · 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.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 2206 (b) 2267 (c) 2197
  3. 3.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  5. 5.What is ∛3375? =
  6. 6.What is 16³? =
  7. 7.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.What is ∛216? =
  9. 9.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  10. 10.What is ∛8? =
  11. 11.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  12. 12.What is ∛343? =
  13. 13.What is 2³? =
  14. 14.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  15. 15.Which of these is a perfect cube? (a) 942 (b) 729 (c) 891
  16. 16.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  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 13³? =
  19. 19.What is 12³? =
  20. 20.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  21. 21.Which of these is a perfect cube? (a) 84 (b) 109 (c) 64
  22. 22.What is ∛512? =
  23. 23.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 1362 (b) 1331 (c) 1428
  25. 25.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  26. 26.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  27. 27.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  28. 28.What is 19³? =
  29. 29.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 1810 (b) 1786 (c) 1728
  31. 31.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  32. 32.What is 11³? =
  33. 33.What is 14³? =
  34. 34.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  35. 35.What is ∛1331? =
  36. 36.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  37. 37.What is 7³? =
  38. 38.What is 20³? =
  39. 39.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  40. 40.What is ∛9261? =

Answer key

  1. 27
  2. 2197
  3. 125
  4. 25
  5. 15
  6. 4096
  7. 125
  8. 6
  9. 18
  10. 2
  11. 13
  12. 7
  13. 8
  14. 49
  15. 729
  16. 4
  17. 125
  18. 2197
  19. 1728
  20. 9
  21. 64
  22. 8
  23. 8
  24. 1331
  25. 7
  26. 216
  27. 4
  28. 6859
  29. 216
  30. 1728
  31. 3
  32. 1331
  33. 2744
  34. 5
  35. 11
  36. 10
  37. 343
  38. 8000
  39. 64
  40. 21

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