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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 852 · 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 cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  2. 2.Which of these is a perfect cube? (a) 53 (b) 27 (c) 39
  3. 3.What is ∛1728? =
  4. 4.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  5. 5.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  6. 6.Which of these is a perfect cube? (a) 1364 (b) 1430 (c) 1331
  7. 7.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  10. 10.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  11. 11.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  13. 13.What is 3³? =
  14. 14.Which of these is a perfect cube? (a) 696 (b) 595 (c) 512
  15. 15.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 2152 (b) 1728 (c) 1826
  17. 17.Which of these is a perfect cube? (a) 4021 (b) 3832 (c) 3375
  18. 18.What is ∛512? =
  19. 19.Which of these is a perfect cube? (a) 64 (b) 74 (c) 69
  20. 20.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  21. 21.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  22. 22.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  23. 23.What is ∛15625? =
  24. 24.What is ∛125? =
  25. 25.Which of these is a perfect cube? (a) 363 (b) 349 (c) 343
  26. 26.What is ∛12167? =
  27. 27.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  30. 30.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  31. 31.What is 13³? =
  32. 32.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  33. 33.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  34. 34.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  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.Which of these is a perfect cube? (a) 929 (b) 832 (c) 729
  37. 37.What is 9³? =
  38. 38.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.What is 10³? =
  40. 40.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?

Answer key

  1. 20
  2. 27
  3. 12
  4. 4
  5. 17
  6. 1331
  7. 64
  8. 8
  9. 7
  10. 49
  11. 125
  12. 7
  13. 27
  14. 512
  15. 2
  16. 1728
  17. 3375
  18. 8
  19. 64
  20. 3
  21. 4
  22. 216
  23. 25
  24. 5
  25. 343
  26. 23
  27. 27
  28. 8
  29. 7
  30. 9
  31. 2197
  32. 3
  33. 4
  34. 8
  35. 64
  36. 729
  37. 729
  38. 216
  39. 1000
  40. 9

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