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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 765 · 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 1125 must be multiplied to get a perfect cube?
  2. 2.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.What is 5³? =
  4. 4.What is ∛4096? =
  5. 5.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  7. 7.Which of these is a perfect cube? (a) 1690 (b) 1331 (c) 1670
  8. 8.What is ∛12167? =
  9. 9.Which of these is a perfect cube? (a) 729 (b) 785 (c) 755
  10. 10.What is ∛9261? =
  11. 11.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  12. 12.Which of these is a perfect cube? (a) 2688 (b) 2197 (c) 2207
  13. 13.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  14. 14.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  16. 16.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  17. 17.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.Which of these is a perfect cube? (a) 343 (b) 446 (c) 428
  19. 19.Which of these is a perfect cube? (a) 1854 (b) 1728 (c) 1744
  20. 20.What is ∛2197? =
  21. 21.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  22. 22.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  23. 23.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  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.What is 4³? =
  26. 26.What is 15³? =
  27. 27.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  28. 28.What is 16³? =
  29. 29.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  30. 30.Which of these is a perfect cube? (a) 130 (b) 125 (c) 170
  31. 31.What is 20³? =
  32. 32.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is 10³? =
  34. 34.What is ∛343? =
  35. 35.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.What is 7³? =
  37. 37.What is 13³? =
  38. 38.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  39. 39.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  40. 40.What is ∛1331? =

Answer key

  1. 3
  2. 216
  3. 125
  4. 16
  5. 216
  6. 2
  7. 1331
  8. 23
  9. 729
  10. 21
  11. 9
  12. 2197
  13. 4
  14. 27
  15. 3
  16. 14
  17. 8
  18. 343
  19. 1728
  20. 13
  21. 5
  22. 125
  23. 4
  24. 64
  25. 64
  26. 3375
  27. 10
  28. 4096
  29. 7
  30. 125
  31. 8000
  32. 216
  33. 1000
  34. 7
  35. 64
  36. 343
  37. 2197
  38. 7
  39. 5
  40. 11

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