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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 395 · 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 big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.What is 20³? =
  3. 3.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  5. 5.What is 19³? =
  6. 6.Which of these is a perfect cube? (a) 49 (b) 27 (c) 40
  7. 7.What is 6³? =
  8. 8.What is ∛13824? =
  9. 9.What is the smallest whole number by which 256 must be multiplied 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.What is 11³? =
  12. 12.What is ∛343? =
  13. 13.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  14. 14.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  15. 15.What is ∛5832? =
  16. 16.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  17. 17.What is ∛15625? =
  18. 18.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  19. 19.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  20. 20.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  21. 21.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  22. 22.Which of these is a perfect cube? (a) 1331 (b) 1405 (c) 1426
  23. 23.What is ∛4913? =
  24. 24.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.What is 16³? =
  26. 26.Which of these is a perfect cube? (a) 541 (b) 512 (c) 697
  27. 27.What is ∛64? =
  28. 28.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  29. 29.Which of these is a perfect cube? (a) 2566 (b) 2197 (c) 2503
  30. 30.What is ∛6859? =
  31. 31.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  32. 32.What is ∛8? =
  33. 33.What is ∛512? =
  34. 34.What is ∛125? =
  35. 35.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  36. 36.What is ∛1728? =
  37. 37.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  39. 39.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  40. 40.What is 3³? =

Answer key

  1. 64
  2. 8000
  3. 125
  4. 25
  5. 6859
  6. 27
  7. 216
  8. 24
  9. 2
  10. 16
  11. 1331
  12. 7
  13. 17
  14. 27
  15. 18
  16. 8
  17. 25
  18. 2
  19. 49
  20. 3
  21. 5
  22. 1331
  23. 17
  24. 27
  25. 4096
  26. 512
  27. 4
  28. 5
  29. 2197
  30. 19
  31. 10
  32. 2
  33. 8
  34. 5
  35. 8
  36. 12
  37. 8
  38. 19
  39. 25
  40. 27

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