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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 30 · 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 ∛27? =
  2. 2.Which of these is a perfect cube? (a) 2408 (b) 2375 (c) 2197
  3. 3.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  4. 4.Which of these is a perfect cube? (a) 64 (b) 100 (c) 109
  5. 5.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.What is ∛15625? =
  7. 7.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  8. 8.What is ∛729? =
  9. 9.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  11. 11.What is 15³? =
  12. 12.Which of these is a perfect cube? (a) 1331 (b) 1415 (c) 1464
  13. 13.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  14. 14.Which of these is a perfect cube? (a) 603 (b) 512 (c) 701
  15. 15.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  16. 16.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  17. 17.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  18. 18.Which of these is a perfect cube? (a) 2744 (b) 2915 (c) 2843
  19. 19.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  20. 20.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  21. 21.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  22. 22.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  23. 23.What is 11³? =
  24. 24.Which of these is a perfect cube? (a) 319 (b) 225 (c) 216
  25. 25.What is ∛4096? =
  26. 26.What is 12³? =
  27. 27.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛343? =
  30. 30.What is ∛5832? =
  31. 31.What is ∛1728? =
  32. 32.What is ∛13824? =
  33. 33.What is 2³? =
  34. 34.What is ∛64? =
  35. 35.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  36. 36.Which of these is a perfect cube? (a) 3792 (b) 3469 (c) 3375
  37. 37.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  38. 38.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  40. 40.What is 17³? =

Answer key

  1. 3
  2. 2197
  3. 25
  4. 64
  5. 27
  6. 25
  7. 3
  8. 9
  9. 125
  10. 216
  11. 3375
  12. 1331
  13. 9
  14. 512
  15. 12
  16. 5
  17. 4
  18. 2744
  19. 7
  20. 9
  21. 10
  22. 5
  23. 1331
  24. 216
  25. 16
  26. 1728
  27. 27
  28. 6
  29. 7
  30. 18
  31. 12
  32. 24
  33. 8
  34. 4
  35. 7
  36. 3375
  37. 9
  38. 8
  39. 3
  40. 4913

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