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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 277 · 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.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  4. 4.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  5. 5.What is ∛10648? =
  6. 6.Which of these is a perfect cube? (a) 3701 (b) 3715 (c) 3375
  7. 7.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  8. 8.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  9. 9.What is ∛1728? =
  10. 10.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  11. 11.What is 2³? =
  12. 12.What is ∛8000? =
  13. 13.What is ∛12167? =
  14. 14.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  15. 15.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  16. 16.What is ∛1000? =
  17. 17.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.Which of these is a perfect cube? (a) 103 (b) 64 (c) 108
  20. 20.Which of these is a perfect cube? (a) 1623 (b) 1331 (c) 1349
  21. 21.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  22. 22.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  23. 23.What is ∛8? =
  24. 24.Which of these is a perfect cube? (a) 1813 (b) 2048 (c) 1728
  25. 25.What is ∛64? =
  26. 26.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  27. 27.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  28. 28.What is ∛4096? =
  29. 29.What is 5³? =
  30. 30.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  31. 31.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  32. 32.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  33. 33.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  35. 35.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  36. 36.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  37. 37.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  38. 38.What is 12³? =
  39. 39.What is 4³? =
  40. 40.What is ∛216? =

Answer key

  1. 27
  2. 64
  3. 3
  4. 9
  5. 22
  6. 3375
  7. 25
  8. 4
  9. 12
  10. 5
  11. 8
  12. 20
  13. 23
  14. 9
  15. 2
  16. 10
  17. 27
  18. 125
  19. 64
  20. 1331
  21. 2
  22. 14
  23. 2
  24. 1728
  25. 4
  26. 10
  27. 13
  28. 16
  29. 125
  30. 12
  31. 3
  32. 125
  33. 8
  34. 7
  35. 4
  36. 49
  37. 20
  38. 1728
  39. 64
  40. 6

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