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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 673 · 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 the smallest whole number by which 320 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  3. 3.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  4. 4.What is 6³? =
  5. 5.Which of these is a perfect cube? (a) 3174 (b) 2744 (c) 2965
  6. 6.Which of these is a perfect cube? (a) 532 (b) 581 (c) 512
  7. 7.What is ∛343? =
  8. 8.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  9. 9.Which of these is a perfect cube? (a) 200 (b) 125 (c) 199
  10. 10.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  11. 11.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  12. 12.What is 16³? =
  13. 13.What is ∛13824? =
  14. 14.What is 18³? =
  15. 15.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  17. 17.What is ∛1728? =
  18. 18.What is 2³? =
  19. 19.Which of these is a perfect cube? (a) 54 (b) 27 (c) 40
  20. 20.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  21. 21.What is ∛1331? =
  22. 22.What is ∛216? =
  23. 23.What is 14³? =
  24. 24.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  26. 26.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  27. 27.What is 10³? =
  28. 28.Which of these is a perfect cube? (a) 1728 (b) 1913 (c) 2145
  29. 29.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  30. 30.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  31. 31.What is 17³? =
  32. 32.What is ∛27? =
  33. 33.What is ∛12167? =
  34. 34.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  36. 36.What is ∛64? =
  37. 37.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  38. 38.What is 3³? =
  39. 39.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  40. 40.Which of these is a perfect cube? (a) 226 (b) 220 (c) 216

Answer key

  1. 25
  2. 3
  3. 4
  4. 216
  5. 2744
  6. 512
  7. 7
  8. 7
  9. 125
  10. 2
  11. 7
  12. 4096
  13. 24
  14. 5832
  15. 216
  16. 9
  17. 12
  18. 8
  19. 27
  20. 3
  21. 11
  22. 6
  23. 2744
  24. 216
  25. 8
  26. 4
  27. 1000
  28. 1728
  29. 17
  30. 4
  31. 4913
  32. 3
  33. 23
  34. 125
  35. 2
  36. 4
  37. 216
  38. 27
  39. 4
  40. 216

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