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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 688 · 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) 27 (b) 47 (c) 38
  3. 3.Which of these is a perfect cube? (a) 3558 (b) 3473 (c) 3375
  4. 4.Which of these is a perfect cube? (a) 1400 (b) 1331 (c) 1544
  5. 5.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  6. 6.What is ∛1331? =
  7. 7.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  8. 8.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  9. 9.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  11. 11.What is ∛64? =
  12. 12.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  13. 13.What is 5³? =
  14. 14.What is ∛8? =
  15. 15.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 2197 (b) 2704 (c) 2555
  17. 17.What is ∛6859? =
  18. 18.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  19. 19.What is ∛15625? =
  20. 20.Which of these is a perfect cube? (a) 833 (b) 747 (c) 729
  21. 21.What is ∛125? =
  22. 22.What is 11³? =
  23. 23.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  24. 24.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  25. 25.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  26. 26.What is 14³? =
  27. 27.What is 3³? =
  28. 28.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  29. 29.What is 6³? =
  30. 30.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  31. 31.Which of these is a perfect cube? (a) 2084 (b) 2150 (c) 1728
  32. 32.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  33. 33.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  34. 34.Which of these is a perfect cube? (a) 64 (b) 77 (c) 93
  35. 35.What is ∛512? =
  36. 36.Which of these is a perfect cube? (a) 264 (b) 262 (c) 216
  37. 37.Which of these is a perfect cube? (a) 462 (b) 444 (c) 343
  38. 38.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  39. 39.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  40. 40.What is 9³? =

Answer key

  1. 20
  2. 27
  3. 3375
  4. 1331
  5. 3
  6. 11
  7. 9
  8. 25
  9. 8
  10. 25
  11. 4
  12. 7
  13. 125
  14. 2
  15. 125
  16. 2197
  17. 19
  18. 5
  19. 25
  20. 729
  21. 5
  22. 1331
  23. 64
  24. 3
  25. 64
  26. 2744
  27. 27
  28. 13
  29. 216
  30. 15
  31. 1728
  32. 9
  33. 125
  34. 64
  35. 8
  36. 216
  37. 343
  38. 5
  39. 11
  40. 729

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