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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 407 · 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 2³? =
  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 ∛3375? =
  4. 4.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  5. 5.What is 6³? =
  6. 6.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  7. 7.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.Which of these is a perfect cube? (a) 3215 (b) 2744 (c) 2910
  9. 9.What is 4³? =
  10. 10.What is 7³? =
  11. 11.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  12. 12.What is 8³? =
  13. 13.What is ∛512? =
  14. 14.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  17. 17.What is 9³? =
  18. 18.What is ∛64? =
  19. 19.Which of these is a perfect cube? (a) 512 (b) 636 (c) 587
  20. 20.Which of these is a perfect cube? (a) 47 (b) 36 (c) 27
  21. 21.What is 14³? =
  22. 22.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  23. 23.What is 11³? =
  24. 24.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  25. 25.What is 15³? =
  26. 26.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  27. 27.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  28. 28.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  29. 29.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  30. 30.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  32. 32.What is ∛12167? =
  33. 33.What is ∛10648? =
  34. 34.What is 10³? =
  35. 35.What is 5³? =
  36. 36.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  37. 37.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  38. 38.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  40. 40.Which of these is a perfect cube? (a) 729 (b) 942 (c) 920

Answer key

  1. 8
  2. 125
  3. 15
  4. 3
  5. 216
  6. 3
  7. 27
  8. 2744
  9. 64
  10. 343
  11. 8
  12. 512
  13. 8
  14. 5
  15. 125
  16. 18
  17. 729
  18. 4
  19. 512
  20. 27
  21. 2744
  22. 7
  23. 1331
  24. 3
  25. 3375
  26. 4
  27. 9
  28. 15
  29. 9
  30. 27
  31. 5
  32. 23
  33. 22
  34. 1000
  35. 125
  36. 6
  37. 2
  38. 64
  39. 49
  40. 729

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