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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 104 · 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 4³? =
  2. 2.What is 3³? =
  3. 3.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  4. 4.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  5. 5.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  6. 6.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  7. 7.What is 8³? =
  8. 8.Which of these is a perfect cube? (a) 1813 (b) 1728 (c) 2148
  9. 9.Which of these is a perfect cube? (a) 64 (b) 91 (c) 86
  10. 10.What is ∛216? =
  11. 11.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  12. 12.What is 15³? =
  13. 13.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  14. 14.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 198 (b) 125 (c) 174
  17. 17.Which of these is a perfect cube? (a) 634 (b) 538 (c) 512
  18. 18.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.Which of these is a perfect cube? (a) 1000 (b) 1022 (c) 1241
  20. 20.Which of these is a perfect cube? (a) 1580 (b) 1331 (c) 1405
  21. 21.What is 9³? =
  22. 22.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  23. 23.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  24. 24.What is ∛512? =
  25. 25.What is ∛8? =
  26. 26.What is ∛4913? =
  27. 27.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  28. 28.What is ∛729? =
  29. 29.What is ∛9261? =
  30. 30.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  31. 31.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  32. 32.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  33. 33.What is 18³? =
  34. 34.What is ∛125? =
  35. 35.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  36. 36.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  37. 37.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.What is ∛12167? =
  39. 39.Which of these is a perfect cube? (a) 216 (b) 322 (c) 226
  40. 40.Which of these is a perfect cube? (a) 2748 (b) 3230 (c) 2744

Answer key

  1. 64
  2. 27
  3. 17
  4. 8
  5. 5
  6. 2
  7. 512
  8. 1728
  9. 64
  10. 6
  11. 27
  12. 3375
  13. 2
  14. 4
  15. 27
  16. 125
  17. 512
  18. 64
  19. 1000
  20. 1331
  21. 729
  22. 13
  23. 7
  24. 8
  25. 2
  26. 17
  27. 25
  28. 9
  29. 21
  30. 9
  31. 5
  32. 3
  33. 5832
  34. 5
  35. 2
  36. 216
  37. 125
  38. 23
  39. 216
  40. 2744

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