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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 554 · 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 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  3. 3.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  4. 4.What is 12³? =
  5. 5.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  6. 6.What is ∛8? =
  7. 7.Which of these is a perfect cube? (a) 917 (b) 729 (c) 934
  8. 8.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.What is ∛27? =
  10. 10.Which of these is a perfect cube? (a) 3061 (b) 2919 (c) 2744
  11. 11.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  12. 12.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  13. 13.What is ∛343? =
  14. 14.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  15. 15.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  16. 16.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  17. 17.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  18. 18.What is ∛1331? =
  19. 19.Which of these is a perfect cube? (a) 1331 (b) 1466 (c) 1473
  20. 20.What is ∛729? =
  21. 21.Which of these is a perfect cube? (a) 216 (b) 223 (c) 311
  22. 22.What is 20³? =
  23. 23.What is 5³? =
  24. 24.Which of these is a perfect cube? (a) 569 (b) 582 (c) 512
  25. 25.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  26. 26.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  27. 27.Which of these is a perfect cube? (a) 343 (b) 489 (c) 390
  28. 28.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  29. 29.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.What is 6³? =
  31. 31.What is ∛6859? =
  32. 32.Which of these is a perfect cube? (a) 27 (b) 42 (c) 45
  33. 33.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  34. 34.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  36. 36.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  38. 38.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  39. 39.What is 13³? =
  40. 40.What is ∛2744? =

Answer key

  1. 125
  2. 9
  3. 2
  4. 1728
  5. 49
  6. 2
  7. 729
  8. 8
  9. 3
  10. 2744
  11. 17
  12. 19
  13. 7
  14. 3
  15. 4
  16. 64
  17. 14
  18. 11
  19. 1331
  20. 9
  21. 216
  22. 8000
  23. 125
  24. 512
  25. 4
  26. 9
  27. 343
  28. 4
  29. 27
  30. 216
  31. 19
  32. 27
  33. 18
  34. 64
  35. 4
  36. 216
  37. 49
  38. 64
  39. 2197
  40. 14

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