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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 672 · 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 189 must be divided to get a perfect cube?
  3. 3.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  4. 4.What is 2³? =
  5. 5.What is ∛10648? =
  6. 6.What is ∛2197? =
  7. 7.Which of these is a perfect cube? (a) 2099 (b) 2009 (c) 1728
  8. 8.Which of these is a perfect cube? (a) 1331 (b) 1648 (c) 1357
  9. 9.Which of these is a perfect cube? (a) 2446 (b) 2197 (c) 2319
  10. 10.What is ∛27? =
  11. 11.What is ∛13824? =
  12. 12.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  13. 13.What is ∛125? =
  14. 14.What is ∛512? =
  15. 15.What is 14³? =
  16. 16.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  17. 17.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  18. 18.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  19. 19.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  20. 20.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  21. 21.What is 20³? =
  22. 22.Which of these is a perfect cube? (a) 27 (b) 29 (c) 30
  23. 23.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  25. 25.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  26. 26.What is ∛2744? =
  27. 27.Which of these is a perfect cube? (a) 935 (b) 949 (c) 729
  28. 28.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is ∛15625? =
  30. 30.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  31. 31.What is 13³? =
  32. 32.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  33. 33.Which of these is a perfect cube? (a) 361 (b) 360 (c) 343
  34. 34.Which of these is a perfect cube? (a) 303 (b) 320 (c) 216
  35. 35.What is ∛1000? =
  36. 36.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  38. 38.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  39. 39.What is 12³? =
  40. 40.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?

Answer key

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

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