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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 819 · 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 448 must be divided to get a perfect cube?
  2. 2.What is ∛27? =
  3. 3.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  4. 4.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  5. 5.What is 3³? =
  6. 6.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  7. 7.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  8. 8.What is 15³? =
  9. 9.Which of these is a perfect cube? (a) 482 (b) 367 (c) 343
  10. 10.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  12. 12.What is ∛216? =
  13. 13.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  14. 14.Which of these is a perfect cube? (a) 965 (b) 938 (c) 729
  15. 15.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  16. 16.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  17. 17.What is ∛4913? =
  18. 18.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  19. 19.What is 11³? =
  20. 20.Which of these is a perfect cube? (a) 3216 (b) 2744 (c) 2916
  21. 21.Which of these is a perfect cube? (a) 1047 (b) 1000 (c) 1039
  22. 22.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  23. 23.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  24. 24.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  25. 25.What is 17³? =
  26. 26.Which of these is a perfect cube? (a) 3848 (b) 3375 (c) 3450
  27. 27.What is ∛6859? =
  28. 28.Which of these is a perfect cube? (a) 216 (b) 239 (c) 233
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  32. 32.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.What is 20³? =
  34. 34.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  37. 37.Which of these is a perfect cube? (a) 704 (b) 512 (c) 514
  38. 38.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.What is 19³? =
  40. 40.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?

Answer key

  1. 7
  2. 3
  3. 25
  4. 5
  5. 27
  6. 3
  7. 11
  8. 3375
  9. 343
  10. 64
  11. 4
  12. 6
  13. 2
  14. 729
  15. 9
  16. 3
  17. 17
  18. 17
  19. 1331
  20. 2744
  21. 1000
  22. 125
  23. 4
  24. 49
  25. 4913
  26. 3375
  27. 19
  28. 216
  29. 8
  30. 125
  31. 49
  32. 216
  33. 8000
  34. 5
  35. 9
  36. 8
  37. 512
  38. 125
  39. 6859
  40. 16

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