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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 530 · 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 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  3. 3.Which of these is a perfect cube? (a) 225 (b) 321 (c) 216
  4. 4.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  5. 5.What is ∛5832? =
  6. 6.What is ∛8? =
  7. 7.What is 10³? =
  8. 8.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  9. 9.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  10. 10.What is ∛216? =
  11. 11.What is 11³? =
  12. 12.Which of these is a perfect cube? (a) 3701 (b) 3417 (c) 3375
  13. 13.Which of these is a perfect cube? (a) 64 (b) 87 (c) 73
  14. 14.What is 2³? =
  15. 15.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  16. 16.What is ∛12167? =
  17. 17.What is ∛9261? =
  18. 18.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  19. 19.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  20. 20.What is 20³? =
  21. 21.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  22. 22.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  23. 23.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 27 (b) 47 (c) 53
  25. 25.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  26. 26.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  27. 27.Which of these is a perfect cube? (a) 1728 (b) 1764 (c) 2049
  28. 28.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  29. 29.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  30. 30.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  31. 31.What is ∛15625? =
  32. 32.What is 7³? =
  33. 33.What is ∛125? =
  34. 34.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  36. 36.What is 18³? =
  37. 37.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  38. 38.Which of these is a perfect cube? (a) 1339 (b) 1614 (c) 1331
  39. 39.What is 4³? =
  40. 40.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?

Answer key

  1. 64
  2. 14
  3. 216
  4. 2
  5. 18
  6. 2
  7. 1000
  8. 9
  9. 10
  10. 6
  11. 1331
  12. 3375
  13. 64
  14. 8
  15. 18
  16. 23
  17. 21
  18. 125
  19. 2
  20. 8000
  21. 4
  22. 13
  23. 49
  24. 27
  25. 3
  26. 8
  27. 1728
  28. 19
  29. 16
  30. 4
  31. 25
  32. 343
  33. 5
  34. 27
  35. 15
  36. 5832
  37. 125
  38. 1331
  39. 64
  40. 49

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