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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 985 · 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 the smallest whole number by which 1512 must be divided to get a perfect cube?
  2. 2.What is 3³? =
  3. 3.What is ∛9261? =
  4. 4.What is ∛13824? =
  5. 5.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 80 (b) 83 (c) 64
  7. 7.Which of these is a perfect cube? (a) 1040 (b) 1000 (c) 1149
  8. 8.Which of these is a perfect cube? (a) 1331 (b) 1658 (c) 1500
  9. 9.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  10. 10.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  11. 11.Which of these is a perfect cube? (a) 3041 (b) 3045 (c) 2744
  12. 12.What is 8³? =
  13. 13.What is ∛10648? =
  14. 14.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  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) 2508 (b) 2677 (c) 2197
  17. 17.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  18. 18.Which of these is a perfect cube? (a) 130 (b) 125 (c) 194
  19. 19.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  20. 20.What is ∛125? =
  21. 21.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  22. 22.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  23. 23.Which of these is a perfect cube? (a) 887 (b) 729 (c) 945
  24. 24.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  25. 25.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  26. 26.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  27. 27.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  28. 28.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛729? =
  30. 30.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  31. 31.What is ∛1728? =
  32. 32.What is 12³? =
  33. 33.What is ∛2744? =
  34. 34.What is 13³? =
  35. 35.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  36. 36.What is ∛3375? =
  37. 37.What is 15³? =
  38. 38.What is 9³? =
  39. 39.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.What is ∛27? =

Answer key

  1. 7
  2. 27
  3. 21
  4. 24
  5. 125
  6. 64
  7. 1000
  8. 1331
  9. 49
  10. 16
  11. 2744
  12. 512
  13. 22
  14. 216
  15. 125
  16. 2197
  17. 2
  18. 125
  19. 49
  20. 5
  21. 2
  22. 7
  23. 729
  24. 7
  25. 4
  26. 7
  27. 11
  28. 2
  29. 9
  30. 5
  31. 12
  32. 1728
  33. 14
  34. 2197
  35. 10
  36. 15
  37. 3375
  38. 729
  39. 8
  40. 3

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