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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 138 · 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 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  3. 3.What is ∛8000? =
  4. 4.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.What is 5³? =
  6. 6.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  7. 7.Which of these is a perfect cube? (a) 150 (b) 125 (c) 131
  8. 8.What is ∛125? =
  9. 9.What is ∛1000? =
  10. 10.What is 7³? =
  11. 11.What is ∛5832? =
  12. 12.What is ∛343? =
  13. 13.What is ∛13824? =
  14. 14.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 1367 (b) 1519 (c) 1331
  17. 17.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is 13³? =
  19. 19.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  20. 20.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  21. 21.What is 10³? =
  22. 22.What is ∛4096? =
  23. 23.Which of these is a perfect cube? (a) 276 (b) 216 (c) 269
  24. 24.What is 18³? =
  25. 25.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  26. 26.What is 8³? =
  27. 27.What is ∛216? =
  28. 28.What is ∛10648? =
  29. 29.Which of these is a perfect cube? (a) 2197 (b) 2390 (c) 2499
  30. 30.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  31. 31.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  32. 32.What is ∛512? =
  33. 33.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  34. 34.Which of these is a perfect cube? (a) 49 (b) 41 (c) 27
  35. 35.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  36. 36.What is ∛64? =
  37. 37.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  38. 38.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  39. 39.What is ∛729? =
  40. 40.Which of these is a perfect cube? (a) 365 (b) 351 (c) 343

Answer key

  1. 125
  2. 25
  3. 20
  4. 8
  5. 125
  6. 5
  7. 125
  8. 5
  9. 10
  10. 343
  11. 18
  12. 7
  13. 24
  14. 9
  15. 216
  16. 1331
  17. 27
  18. 2197
  19. 10
  20. 3
  21. 1000
  22. 16
  23. 216
  24. 5832
  25. 49
  26. 512
  27. 6
  28. 22
  29. 2197
  30. 64
  31. 4
  32. 8
  33. 3
  34. 27
  35. 25
  36. 4
  37. 8
  38. 125
  39. 9
  40. 343

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