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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 698 · 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 8³? =
  2. 2.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.What is 15³? =
  4. 4.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  5. 5.What is 6³? =
  6. 6.Which of these is a perfect cube? (a) 729 (b) 875 (c) 752
  7. 7.What is 7³? =
  8. 8.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  9. 9.What is ∛64? =
  10. 10.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  11. 11.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  12. 12.What is 12³? =
  13. 13.What is ∛512? =
  14. 14.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  15. 15.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 27 (b) 43 (c) 42
  17. 17.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.What is 17³? =
  19. 19.What is ∛216? =
  20. 20.What is ∛3375? =
  21. 21.What is 10³? =
  22. 22.What is ∛9261? =
  23. 23.Which of these is a perfect cube? (a) 125 (b) 169 (c) 161
  24. 24.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  25. 25.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  26. 26.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  27. 27.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.Which of these is a perfect cube? (a) 1436 (b) 1403 (c) 1331
  29. 29.What is ∛1728? =
  30. 30.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  31. 31.Which of these is a perfect cube? (a) 256 (b) 216 (c) 307
  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 16³? =
  34. 34.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  35. 35.Which of these is a perfect cube? (a) 535 (b) 581 (c) 512
  36. 36.What is 5³? =
  37. 37.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  39. 39.What is 4³? =
  40. 40.What is 11³? =

Answer key

  1. 512
  2. 27
  3. 3375
  4. 49
  5. 216
  6. 729
  7. 343
  8. 5
  9. 4
  10. 12
  11. 7
  12. 1728
  13. 8
  14. 4
  15. 49
  16. 27
  17. 216
  18. 4913
  19. 6
  20. 15
  21. 1000
  22. 21
  23. 125
  24. 64
  25. 49
  26. 3
  27. 8
  28. 1331
  29. 12
  30. 8
  31. 216
  32. 216
  33. 4096
  34. 8
  35. 512
  36. 125
  37. 19
  38. 7
  39. 64
  40. 1331

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