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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 825 · 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.Which of these is a perfect cube? (a) 255 (b) 229 (c) 216
  2. 2.Which of these is a perfect cube? (a) 64 (b) 75 (c) 66
  3. 3.Which of these is a perfect cube? (a) 169 (b) 174 (c) 125
  4. 4.What is ∛729? =
  5. 5.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.Which of these is a perfect cube? (a) 3208 (b) 3241 (c) 2744
  8. 8.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  10. 10.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  11. 11.Which of these is a perfect cube? (a) 1728 (b) 2118 (c) 1770
  12. 12.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  13. 13.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  14. 14.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.Which of these is a perfect cube? (a) 906 (b) 833 (c) 729
  16. 16.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  17. 17.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  18. 18.What is 3³? =
  19. 19.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  20. 20.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  22. 22.What is ∛1000? =
  23. 23.What is ∛512? =
  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 16 must be multiplied to get a perfect cube?
  26. 26.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  27. 27.What is 4³? =
  28. 28.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛125? =
  30. 30.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  31. 31.What is ∛5832? =
  32. 32.What is ∛8000? =
  33. 33.What is 17³? =
  34. 34.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.What is ∛10648? =
  36. 36.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  38. 38.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?

Answer key

  1. 216
  2. 64
  3. 125
  4. 9
  5. 8
  6. 8
  7. 2744
  8. 216
  9. 2
  10. 11
  11. 1728
  12. 9
  13. 125
  14. 64
  15. 729
  16. 7
  17. 19
  18. 27
  19. 49
  20. 6
  21. 216
  22. 10
  23. 8
  24. 9
  25. 4
  26. 7
  27. 64
  28. 8
  29. 5
  30. 5
  31. 18
  32. 20
  33. 4913
  34. 8
  35. 22
  36. 8
  37. 25
  38. 4
  39. 4
  40. 3

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