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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 919 · 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 ∛729? =
  2. 2.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  3. 3.Which of these is a perfect cube? (a) 216 (b) 241 (c) 240
  4. 4.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  5. 5.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  6. 6.What is 3³? =
  7. 7.What is ∛15625? =
  8. 8.What is 10³? =
  9. 9.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  10. 10.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  11. 11.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  14. 14.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  15. 15.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  16. 16.What is 2³? =
  17. 17.What is ∛125? =
  18. 18.What is 12³? =
  19. 19.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  20. 20.What is 4³? =
  21. 21.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  22. 22.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  23. 23.What is 13³? =
  24. 24.Which of these is a perfect cube? (a) 2590 (b) 2197 (c) 2278
  25. 25.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  26. 26.What is ∛5832? =
  27. 27.What is 14³? =
  28. 28.What is 17³? =
  29. 29.What is 5³? =
  30. 30.Which of these is a perfect cube? (a) 1728 (b) 2154 (c) 1857
  31. 31.What is ∛343? =
  32. 32.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  33. 33.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  34. 34.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  35. 35.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  36. 36.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  37. 37.Which of these is a perfect cube? (a) 170 (b) 125 (c) 131
  38. 38.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  40. 40.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 9
  2. 49
  3. 216
  4. 49
  5. 20
  6. 27
  7. 25
  8. 1000
  9. 9
  10. 25
  11. 64
  12. 216
  13. 4
  14. 9
  15. 64
  16. 8
  17. 5
  18. 1728
  19. 5
  20. 64
  21. 15
  22. 27
  23. 2197
  24. 2197
  25. 25
  26. 18
  27. 2744
  28. 4913
  29. 125
  30. 1728
  31. 7
  32. 9
  33. 5
  34. 64
  35. 7
  36. 125
  37. 125
  38. 64
  39. 27
  40. 8

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