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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 748 · 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 11³? =
  2. 2.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  3. 3.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  4. 4.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  5. 5.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  6. 6.What is ∛4096? =
  7. 7.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.What is 15³? =
  9. 9.What is 20³? =
  10. 10.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is ∛343? =
  12. 12.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  14. 14.Which of these is a perfect cube? (a) 835 (b) 729 (c) 812
  15. 15.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  16. 16.What is the smallest whole number by which 135 must be divided to get a perfect cube?
  17. 17.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  18. 18.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  19. 19.What is ∛125? =
  20. 20.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  21. 21.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛15625? =
  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 the smallest whole number by which 128 must be multiplied to get a perfect cube?
  25. 25.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  26. 26.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  27. 27.What is ∛2744? =
  28. 28.What is ∛5832? =
  29. 29.What is 10³? =
  30. 30.What is 3³? =
  31. 31.What is 9³? =
  32. 32.What is ∛8? =
  33. 33.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  35. 35.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  36. 36.Which of these is a perfect cube? (a) 93 (b) 64 (c) 111
  37. 37.Which of these is a perfect cube? (a) 2744 (b) 2912 (c) 3053
  38. 38.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  39. 39.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  40. 40.Which of these is a perfect cube? (a) 2229 (b) 2197 (c) 2245

Answer key

  1. 1331
  2. 49
  3. 2
  4. 15
  5. 5
  6. 16
  7. 64
  8. 3375
  9. 8000
  10. 8
  11. 7
  12. 8
  13. 19
  14. 729
  15. 49
  16. 5
  17. 49
  18. 16
  19. 5
  20. 8
  21. 20
  22. 25
  23. 125
  24. 4
  25. 2
  26. 4
  27. 14
  28. 18
  29. 1000
  30. 27
  31. 729
  32. 2
  33. 27
  34. 10
  35. 5
  36. 64
  37. 2744
  38. 13
  39. 2
  40. 2197

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