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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 42 · 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 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is ∛3375? =
  3. 3.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  5. 5.What is 16³? =
  6. 6.What is 18³? =
  7. 7.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  8. 8.Which of these is a perfect cube? (a) 238 (b) 293 (c) 216
  9. 9.What is ∛729? =
  10. 10.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is 10³? =
  12. 12.Which of these is a perfect cube? (a) 343 (b) 427 (c) 380
  13. 13.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  14. 14.What is ∛4913? =
  15. 15.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  17. 17.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  18. 18.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  19. 19.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  20. 20.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  21. 21.Which of these is a perfect cube? (a) 759 (b) 831 (c) 729
  22. 22.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  23. 23.What is ∛2197? =
  24. 24.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  25. 25.What is ∛216? =
  26. 26.What is ∛9261? =
  27. 27.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  28. 28.What is 12³? =
  29. 29.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  32. 32.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  33. 33.What is ∛8000? =
  34. 34.What is 8³? =
  35. 35.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  36. 36.Which of these is a perfect cube? (a) 2197 (b) 2479 (c) 2680
  37. 37.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  38. 38.What is ∛4096? =
  39. 39.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  40. 40.What is ∛27? =

Answer key

  1. 125
  2. 15
  3. 8
  4. 14
  5. 4096
  6. 5832
  7. 19
  8. 216
  9. 9
  10. 125
  11. 1000
  12. 343
  13. 12
  14. 17
  15. 8
  16. 25
  17. 9
  18. 8
  19. 17
  20. 216
  21. 729
  22. 4
  23. 13
  24. 13
  25. 6
  26. 21
  27. 5
  28. 1728
  29. 8
  30. 3
  31. 49
  32. 3
  33. 20
  34. 512
  35. 3
  36. 2197
  37. 2
  38. 16
  39. 25
  40. 3

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