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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 955 · 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 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  4. 4.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  5. 5.What is ∛2197? =
  6. 6.Which of these is a perfect cube? (a) 424 (b) 402 (c) 343
  7. 7.What is ∛343? =
  8. 8.Which of these is a perfect cube? (a) 512 (b) 648 (c) 619
  9. 9.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  10. 10.What is 7³? =
  11. 11.Which of these is a perfect cube? (a) 29 (b) 27 (c) 40
  12. 12.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  13. 13.What is ∛2744? =
  14. 14.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  16. 16.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  17. 17.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  18. 18.What is 9³? =
  19. 19.What is 2³? =
  20. 20.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  21. 21.What is ∛6859? =
  22. 22.What is 14³? =
  23. 23.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  24. 24.What is ∛1331? =
  25. 25.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  26. 26.What is 10³? =
  27. 27.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛1000? =
  30. 30.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  31. 31.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  32. 32.Which of these is a perfect cube? (a) 125 (b) 140 (c) 142
  33. 33.What is 12³? =
  34. 34.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 1000 (b) 1186 (c) 1268
  36. 36.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.What is 19³? =
  38. 38.What is 16³? =
  39. 39.What is 6³? =
  40. 40.What is 20³? =

Answer key

  1. 125
  2. 125
  3. 4
  4. 27
  5. 13
  6. 343
  7. 7
  8. 512
  9. 3
  10. 343
  11. 27
  12. 5
  13. 14
  14. 64
  15. 2
  16. 20
  17. 18
  18. 729
  19. 8
  20. 4
  21. 19
  22. 2744
  23. 25
  24. 11
  25. 216
  26. 1000
  27. 64
  28. 7
  29. 10
  30. 27
  31. 15
  32. 125
  33. 1728
  34. 49
  35. 1000
  36. 27
  37. 6859
  38. 4096
  39. 216
  40. 8000

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