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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 229 · 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 19³? =
  2. 2.What is 2³? =
  3. 3.What is ∛27? =
  4. 4.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  5. 5.Which of these is a perfect cube? (a) 1204 (b) 1000 (c) 1066
  6. 6.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  7. 7.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.Which of these is a perfect cube? (a) 184 (b) 194 (c) 125
  10. 10.What is 10³? =
  11. 11.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  12. 12.Which of these is a perfect cube? (a) 307 (b) 304 (c) 216
  13. 13.What is 18³? =
  14. 14.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  15. 15.What is 6³? =
  16. 16.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  17. 17.Which of these is a perfect cube? (a) 2802 (b) 2752 (c) 2744
  18. 18.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  19. 19.Which of these is a perfect cube? (a) 968 (b) 729 (c) 740
  20. 20.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  21. 21.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  22. 22.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  23. 23.What is ∛512? =
  24. 24.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  25. 25.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  26. 26.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  27. 27.What is ∛729? =
  28. 28.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  29. 29.What is 4³? =
  30. 30.What is ∛125? =
  31. 31.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  32. 32.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.What is ∛6859? =
  36. 36.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  37. 37.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  38. 38.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  40. 40.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?

Answer key

  1. 6859
  2. 8
  3. 3
  4. 2
  5. 1000
  6. 25
  7. 8
  8. 216
  9. 125
  10. 1000
  11. 11
  12. 216
  13. 5832
  14. 4
  15. 216
  16. 4
  17. 2744
  18. 9
  19. 729
  20. 4
  21. 25
  22. 10
  23. 8
  24. 64
  25. 8
  26. 5
  27. 9
  28. 9
  29. 64
  30. 5
  31. 12
  32. 64
  33. 8
  34. 216
  35. 19
  36. 9
  37. 7
  38. 25
  39. 7
  40. 25

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