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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 459 · 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 2 must be divided to get a perfect cube?
  2. 2.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  3. 3.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  4. 4.A big cube of edge 4 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 1600 must be divided to get a perfect cube?
  6. 6.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  7. 7.What is ∛27? =
  8. 8.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.What is 10³? =
  11. 11.What is ∛64? =
  12. 12.What is 13³? =
  13. 13.What is 9³? =
  14. 14.Which of these is a perfect cube? (a) 932 (b) 777 (c) 729
  15. 15.What is ∛216? =
  16. 16.What is 19³? =
  17. 17.Which of these is a perfect cube? (a) 3542 (b) 3375 (c) 3387
  18. 18.What is ∛10648? =
  19. 19.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  20. 20.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  21. 21.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  22. 22.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  23. 23.Which of these is a perfect cube? (a) 35 (b) 27 (c) 48
  24. 24.What is 14³? =
  25. 25.Which of these is a perfect cube? (a) 64 (b) 88 (c) 89
  26. 26.What is 2³? =
  27. 27.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  28. 28.What is 7³? =
  29. 29.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  30. 30.What is 12³? =
  31. 31.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  32. 32.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  33. 33.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  35. 35.What is 20³? =
  36. 36.What is 15³? =
  37. 37.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  38. 38.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  39. 39.What is ∛8? =
  40. 40.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?

Answer key

  1. 2
  2. 125
  3. 3
  4. 64
  5. 25
  6. 125
  7. 3
  8. 64
  9. 216
  10. 1000
  11. 4
  12. 2197
  13. 729
  14. 729
  15. 6
  16. 6859
  17. 3375
  18. 22
  19. 4
  20. 8
  21. 10
  22. 25
  23. 27
  24. 2744
  25. 64
  26. 8
  27. 6
  28. 343
  29. 49
  30. 1728
  31. 17
  32. 9
  33. 64
  34. 2
  35. 8000
  36. 3375
  37. 2
  38. 2
  39. 2
  40. 12

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