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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 782 · 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 cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  2. 2.Which of these is a perfect cube? (a) 483 (b) 402 (c) 343
  3. 3.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  4. 4.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  5. 5.What is ∛27? =
  6. 6.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  7. 7.What is ∛343? =
  8. 8.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  9. 9.What is 10³? =
  10. 10.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  11. 11.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  13. 13.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  14. 14.What is 18³? =
  15. 15.Which of these is a perfect cube? (a) 133 (b) 127 (c) 125
  16. 16.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  17. 17.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  18. 18.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  19. 19.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  21. 21.Which of these is a perfect cube? (a) 1032 (b) 1001 (c) 1000
  22. 22.Which of these is a perfect cube? (a) 947 (b) 729 (c) 772
  23. 23.What is ∛1000? =
  24. 24.What is 3³? =
  25. 25.What is ∛8000? =
  26. 26.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  27. 27.Which of these is a perfect cube? (a) 1645 (b) 1576 (c) 1331
  28. 28.What is ∛1728? =
  29. 29.What is 16³? =
  30. 30.Which of these is a perfect cube? (a) 81 (b) 83 (c) 64
  31. 31.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  32. 32.What is 5³? =
  33. 33.What is 7³? =
  34. 34.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  36. 36.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  37. 37.What is ∛10648? =
  38. 38.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  39. 39.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  40. 40.Which of these is a perfect cube? (a) 27 (b) 42 (c) 33

Answer key

  1. 10
  2. 343
  3. 8
  4. 8
  5. 3
  6. 27
  7. 7
  8. 2
  9. 1000
  10. 2
  11. 216
  12. 2
  13. 7
  14. 5832
  15. 125
  16. 3
  17. 9
  18. 7
  19. 125
  20. 13
  21. 1000
  22. 729
  23. 10
  24. 27
  25. 20
  26. 3
  27. 1331
  28. 12
  29. 4096
  30. 64
  31. 20
  32. 125
  33. 343
  34. 64
  35. 11
  36. 27
  37. 22
  38. 15
  39. 64
  40. 27

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