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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 556 · 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 ∛125? =
  2. 2.Which of these is a perfect cube? (a) 814 (b) 839 (c) 729
  3. 3.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  4. 4.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.What is ∛6859? =
  6. 6.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  7. 7.Which of these is a perfect cube? (a) 45 (b) 27 (c) 52
  8. 8.What is ∛13824? =
  9. 9.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is ∛15625? =
  12. 12.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  13. 13.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  14. 14.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  16. 16.What is 8³? =
  17. 17.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  18. 18.What is ∛27? =
  19. 19.What is 19³? =
  20. 20.What is ∛2744? =
  21. 21.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  22. 22.What is ∛1728? =
  23. 23.What is 11³? =
  24. 24.Which of these is a perfect cube? (a) 3136 (b) 2744 (c) 3015
  25. 25.What is 20³? =
  26. 26.What is ∛512? =
  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.What is ∛8? =
  29. 29.What is 5³? =
  30. 30.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  31. 31.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  32. 32.Which of these is a perfect cube? (a) 91 (b) 64 (c) 72
  33. 33.What is 9³? =
  34. 34.Which of these is a perfect cube? (a) 3934 (b) 3375 (c) 3383
  35. 35.What is 13³? =
  36. 36.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  37. 37.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  38. 38.What is ∛343? =
  39. 39.What is ∛8000? =
  40. 40.What is 7³? =

Answer key

  1. 5
  2. 729
  3. 11
  4. 27
  5. 19
  6. 4
  7. 27
  8. 24
  9. 216
  10. 8
  11. 25
  12. 8
  13. 216
  14. 64
  15. 5
  16. 512
  17. 49
  18. 3
  19. 6859
  20. 14
  21. 8
  22. 12
  23. 1331
  24. 2744
  25. 8000
  26. 8
  27. 27
  28. 2
  29. 125
  30. 125
  31. 216
  32. 64
  33. 729
  34. 3375
  35. 2197
  36. 3
  37. 15
  38. 7
  39. 20
  40. 343

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