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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 355 · 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 the smallest whole number by which 72 must be multiplied to get a perfect cube?
  2. 2.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  3. 3.What is ∛343? =
  4. 4.What is ∛1331? =
  5. 5.What is 19³? =
  6. 6.Which of these is a perfect cube? (a) 2798 (b) 2744 (c) 2991
  7. 7.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.What is 3³? =
  9. 9.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.What is 11³? =
  11. 11.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  12. 12.What is ∛27? =
  13. 13.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  14. 14.What is ∛4913? =
  15. 15.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  16. 16.What is 5³? =
  17. 17.What is ∛8000? =
  18. 18.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  19. 19.What is 16³? =
  20. 20.Which of these is a perfect cube? (a) 1025 (b) 1000 (c) 1196
  21. 21.Which of these is a perfect cube? (a) 90 (b) 64 (c) 107
  22. 22.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  23. 23.What is 2³? =
  24. 24.What is 17³? =
  25. 25.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  26. 26.What is 10³? =
  27. 27.What is 4³? =
  28. 28.What is ∛2744? =
  29. 29.Which of these is a perfect cube? (a) 125 (b) 152 (c) 191
  30. 30.What is ∛15625? =
  31. 31.Which of these is a perfect cube? (a) 27 (b) 40 (c) 31
  32. 32.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  33. 33.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  34. 34.What is 12³? =
  35. 35.What is 6³? =
  36. 36.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  37. 37.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  38. 38.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  39. 39.What is 15³? =
  40. 40.What is ∛10648? =

Answer key

  1. 3
  2. 7
  3. 7
  4. 11
  5. 6859
  6. 2744
  7. 216
  8. 27
  9. 8
  10. 1331
  11. 10
  12. 3
  13. 9
  14. 17
  15. 8
  16. 125
  17. 20
  18. 13
  19. 4096
  20. 1000
  21. 64
  22. 7
  23. 8
  24. 4913
  25. 7
  26. 1000
  27. 64
  28. 14
  29. 125
  30. 25
  31. 27
  32. 216
  33. 20
  34. 1728
  35. 216
  36. 4
  37. 2
  38. 27
  39. 3375
  40. 22

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