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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 842 · 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 18³? =
  2. 2.What is 10³? =
  3. 3.Which of these is a perfect cube? (a) 33 (b) 27 (c) 43
  4. 4.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  5. 5.Which of these is a perfect cube? (a) 1581 (b) 1331 (c) 1548
  6. 6.What is 2³? =
  7. 7.What is ∛216? =
  8. 8.What is 19³? =
  9. 9.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  10. 10.What is ∛1000? =
  11. 11.What is ∛2197? =
  12. 12.What is ∛10648? =
  13. 13.Which of these is a perfect cube? (a) 2414 (b) 2197 (c) 2651
  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.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  17. 17.Which of these is a perfect cube? (a) 67 (b) 73 (c) 64
  18. 18.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  19. 19.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  20. 20.What is ∛343? =
  21. 21.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  22. 22.What is 11³? =
  23. 23.What is 13³? =
  24. 24.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  25. 25.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  26. 26.What is 4³? =
  27. 27.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  28. 28.What is ∛2744? =
  29. 29.Which of these is a perfect cube? (a) 1000 (b) 1226 (c) 1217
  30. 30.What is ∛64? =
  31. 31.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  32. 32.What is ∛1331? =
  33. 33.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  35. 35.What is ∛8000? =
  36. 36.What is the smallest whole number by which 135 must be divided to get a perfect cube?
  37. 37.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.What is 20³? =
  39. 39.Which of these is a perfect cube? (a) 1803 (b) 1880 (c) 1728
  40. 40.What is 7³? =

Answer key

  1. 5832
  2. 1000
  3. 27
  4. 2
  5. 1331
  6. 8
  7. 6
  8. 6859
  9. 5
  10. 10
  11. 13
  12. 22
  13. 2197
  14. 8
  15. 27
  16. 7
  17. 64
  18. 6
  19. 9
  20. 7
  21. 10
  22. 1331
  23. 2197
  24. 25
  25. 5
  26. 64
  27. 5
  28. 14
  29. 1000
  30. 4
  31. 216
  32. 11
  33. 216
  34. 5
  35. 20
  36. 5
  37. 64
  38. 8000
  39. 1728
  40. 343

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