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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 850 · 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 9³? =
  2. 2.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  3. 3.What is 19³? =
  4. 4.What is ∛125? =
  5. 5.What is 10³? =
  6. 6.What is ∛64? =
  7. 7.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  8. 8.Which of these is a perfect cube? (a) 1036 (b) 1049 (c) 1000
  9. 9.Which of these is a perfect cube? (a) 695 (b) 512 (c) 534
  10. 10.What is 11³? =
  11. 11.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.Which of these is a perfect cube? (a) 1728 (b) 1762 (c) 2010
  14. 14.What is ∛2744? =
  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 4³? =
  17. 17.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  18. 18.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  19. 19.What is ∛512? =
  20. 20.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  21. 21.What is ∛8000? =
  22. 22.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  23. 23.What is 5³? =
  24. 24.What is ∛27? =
  25. 25.Which of these is a perfect cube? (a) 64 (b) 79 (c) 70
  26. 26.Which of these is a perfect cube? (a) 2197 (b) 2604 (c) 2608
  27. 27.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.Which of these is a perfect cube? (a) 903 (b) 729 (c) 791
  29. 29.What is 7³? =
  30. 30.What is 18³? =
  31. 31.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  32. 32.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  33. 33.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  34. 34.Which of these is a perfect cube? (a) 31 (b) 27 (c) 39
  35. 35.What is ∛9261? =
  36. 36.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  37. 37.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  39. 39.What is 8³? =
  40. 40.What is the smallest whole number by which 135 must be divided to get a perfect cube?

Answer key

  1. 729
  2. 125
  3. 6859
  4. 5
  5. 1000
  6. 4
  7. 2
  8. 1000
  9. 512
  10. 1331
  11. 27
  12. 216
  13. 1728
  14. 14
  15. 27
  16. 64
  17. 5
  18. 4
  19. 8
  20. 64
  21. 20
  22. 8
  23. 125
  24. 3
  25. 64
  26. 2197
  27. 8
  28. 729
  29. 343
  30. 5832
  31. 2
  32. 7
  33. 9
  34. 27
  35. 21
  36. 9
  37. 7
  38. 2
  39. 512
  40. 5

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