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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 390 · 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 17³? =
  2. 2.What is ∛1331? =
  3. 3.What is 13³? =
  4. 4.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  5. 5.What is ∛216? =
  6. 6.What is ∛3375? =
  7. 7.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  8. 8.What is 4³? =
  9. 9.What is ∛27? =
  10. 10.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.Which of these is a perfect cube? (a) 1019 (b) 1236 (c) 1000
  12. 12.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is 15³? =
  14. 14.What is ∛343? =
  15. 15.What is ∛8000? =
  16. 16.Which of these is a perfect cube? (a) 216 (b) 324 (c) 319
  17. 17.What is 7³? =
  18. 18.What is 10³? =
  19. 19.Which of these is a perfect cube? (a) 1557 (b) 1392 (c) 1331
  20. 20.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  21. 21.Which of these is a perfect cube? (a) 145 (b) 173 (c) 125
  22. 22.What is 9³? =
  23. 23.What is ∛1000? =
  24. 24.Which of these is a perfect cube? (a) 343 (b) 355 (c) 380
  25. 25.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 53 (b) 52 (c) 27
  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 1728 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛64? =
  30. 30.What is 11³? =
  31. 31.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  34. 34.What is ∛1728? =
  35. 35.What is 14³? =
  36. 36.What is 3³? =
  37. 37.What is 6³? =
  38. 38.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  39. 39.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  40. 40.What is the smallest whole number by which 675 must be divided to get a perfect cube?

Answer key

  1. 4913
  2. 11
  3. 2197
  4. 25
  5. 6
  6. 15
  7. 5
  8. 64
  9. 3
  10. 8
  11. 1000
  12. 125
  13. 3375
  14. 7
  15. 20
  16. 216
  17. 343
  18. 1000
  19. 1331
  20. 125
  21. 125
  22. 729
  23. 10
  24. 343
  25. 5
  26. 27
  27. 64
  28. 12
  29. 4
  30. 1331
  31. 17
  32. 27
  33. 2
  34. 12
  35. 2744
  36. 27
  37. 216
  38. 3
  39. 2
  40. 25

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