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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 276 · 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 ∛125? =
  2. 2.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  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.What is 20³? =
  5. 5.What is ∛9261? =
  6. 6.What is ∛8000? =
  7. 7.Which of these is a perfect cube? (a) 729 (b) 791 (c) 913
  8. 8.Which of these is a perfect cube? (a) 512 (b) 566 (c) 538
  9. 9.What is ∛10648? =
  10. 10.What is 4³? =
  11. 11.What is 10³? =
  12. 12.Which of these is a perfect cube? (a) 343 (b) 382 (c) 425
  13. 13.Which of these is a perfect cube? (a) 40 (b) 27 (c) 50
  14. 14.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  15. 15.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  17. 17.What is ∛343? =
  18. 18.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  19. 19.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  20. 20.What is ∛2744? =
  21. 21.What is 19³? =
  22. 22.What is ∛4913? =
  23. 23.What is ∛6859? =
  24. 24.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  25. 25.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  26. 26.What is ∛1331? =
  27. 27.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  28. 28.What is 12³? =
  29. 29.What is 15³? =
  30. 30.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  31. 31.What is 3³? =
  32. 32.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  33. 33.What is 14³? =
  34. 34.What is 2³? =
  35. 35.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  36. 36.What is ∛12167? =
  37. 37.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  38. 38.What is ∛2197? =
  39. 39.Which of these is a perfect cube? (a) 2800 (b) 2744 (c) 2812
  40. 40.What is ∛512? =

Answer key

  1. 5
  2. 64
  3. 8
  4. 8000
  5. 21
  6. 20
  7. 729
  8. 512
  9. 22
  10. 64
  11. 1000
  12. 343
  13. 27
  14. 64
  15. 8
  16. 4
  17. 7
  18. 16
  19. 8
  20. 14
  21. 6859
  22. 17
  23. 19
  24. 18
  25. 8
  26. 11
  27. 25
  28. 1728
  29. 3375
  30. 4
  31. 27
  32. 5
  33. 2744
  34. 8
  35. 9
  36. 23
  37. 9
  38. 13
  39. 2744
  40. 8

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