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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 681 · 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 250 must be divided to get a perfect cube?
  2. 2.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  3. 3.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  4. 4.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  5. 5.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  7. 7.What is 19³? =
  8. 8.What is ∛64? =
  9. 9.What is 20³? =
  10. 10.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  11. 11.What is 4³? =
  12. 12.Which of these is a perfect cube? (a) 875 (b) 833 (c) 729
  13. 13.Which of these is a perfect cube? (a) 38 (b) 41 (c) 27
  14. 14.Which of these is a perfect cube? (a) 419 (b) 433 (c) 343
  15. 15.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  17. 17.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  18. 18.Which of these is a perfect cube? (a) 1853 (b) 1768 (c) 1728
  19. 19.Which of these is a perfect cube? (a) 3433 (b) 3375 (c) 3940
  20. 20.What is 7³? =
  21. 21.Which of these is a perfect cube? (a) 2197 (b) 2513 (c) 2280
  22. 22.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  23. 23.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is 8³? =
  25. 25.What is 11³? =
  26. 26.What is ∛343? =
  27. 27.What is ∛8000? =
  28. 28.What is ∛12167? =
  29. 29.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  30. 30.What is ∛125? =
  31. 31.What is ∛2744? =
  32. 32.Which of these is a perfect cube? (a) 81 (b) 64 (c) 97
  33. 33.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  34. 34.What is 10³? =
  35. 35.What is ∛10648? =
  36. 36.What is ∛729? =
  37. 37.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  38. 38.Which of these is a perfect cube? (a) 650 (b) 512 (c) 542
  39. 39.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  40. 40.What is ∛6859? =

Answer key

  1. 2
  2. 5
  3. 8
  4. 8
  5. 8
  6. 27
  7. 6859
  8. 4
  9. 8000
  10. 2
  11. 64
  12. 729
  13. 27
  14. 343
  15. 64
  16. 2
  17. 18
  18. 1728
  19. 3375
  20. 343
  21. 2197
  22. 4
  23. 125
  24. 512
  25. 1331
  26. 7
  27. 20
  28. 23
  29. 9
  30. 5
  31. 14
  32. 64
  33. 5
  34. 1000
  35. 22
  36. 9
  37. 3
  38. 512
  39. 3
  40. 19

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