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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 127 · 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.Which of these is a perfect cube? (a) 729 (b) 772 (c) 795
  2. 2.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  3. 3.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  5. 5.What is ∛3375? =
  6. 6.What is 18³? =
  7. 7.What is 13³? =
  8. 8.Which of these is a perfect cube? (a) 149 (b) 125 (c) 150
  9. 9.What is ∛15625? =
  10. 10.What is 12³? =
  11. 11.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  12. 12.What is ∛13824? =
  13. 13.What is 11³? =
  14. 14.What is ∛6859? =
  15. 15.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 2197 (b) 2699 (c) 2294
  17. 17.What is ∛343? =
  18. 18.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  19. 19.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  20. 20.Which of these is a perfect cube? (a) 539 (b) 512 (c) 679
  21. 21.What is ∛27? =
  22. 22.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  23. 23.What is 7³? =
  24. 24.What is ∛2744? =
  25. 25.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  26. 26.What is ∛8000? =
  27. 27.Which of these is a perfect cube? (a) 454 (b) 343 (c) 397
  28. 28.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  30. 30.What is 19³? =
  31. 31.What is ∛729? =
  32. 32.What is ∛9261? =
  33. 33.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  37. 37.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  38. 38.What is 8³? =
  39. 39.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?

Answer key

  1. 729
  2. 5
  3. 64
  4. 7
  5. 15
  6. 5832
  7. 2197
  8. 125
  9. 25
  10. 1728
  11. 25
  12. 24
  13. 1331
  14. 19
  15. 5
  16. 2197
  17. 7
  18. 4
  19. 4
  20. 512
  21. 3
  22. 7
  23. 343
  24. 14
  25. 4
  26. 20
  27. 343
  28. 125
  29. 3
  30. 6859
  31. 9
  32. 21
  33. 27
  34. 25
  35. 2
  36. 3
  37. 3
  38. 512
  39. 49
  40. 15

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