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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 129 · 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 cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  2. 2.What is ∛2744? =
  3. 3.Which of these is a perfect cube? (a) 262 (b) 236 (c) 216
  4. 4.Which of these is a perfect cube? (a) 39 (b) 37 (c) 27
  5. 5.What is 11³? =
  6. 6.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.What is 15³? =
  8. 8.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.Which of these is a perfect cube? (a) 1331 (b) 1547 (c) 1370
  10. 10.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  11. 11.What is 2³? =
  12. 12.What is ∛9261? =
  13. 13.A cube has a volume of 5832 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 7³? =
  16. 16.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  17. 17.Which of these is a perfect cube? (a) 3563 (b) 3375 (c) 3561
  18. 18.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  19. 19.What is 18³? =
  20. 20.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  21. 21.What is 20³? =
  22. 22.What is 10³? =
  23. 23.Which of these is a perfect cube? (a) 2988 (b) 2744 (c) 2836
  24. 24.What is ∛27? =
  25. 25.What is ∛8000? =
  26. 26.What is 5³? =
  27. 27.Which of these is a perfect cube? (a) 2320 (b) 2197 (c) 2465
  28. 28.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  29. 29.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  30. 30.What is ∛2197? =
  31. 31.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  32. 32.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  33. 33.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  34. 34.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  35. 35.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  36. 36.Which of these is a perfect cube? (a) 145 (b) 185 (c) 125
  37. 37.Which of these is a perfect cube? (a) 1800 (b) 1728 (c) 2096
  38. 38.What is ∛4913? =
  39. 39.Which of these is a perfect cube? (a) 512 (b) 553 (c) 527
  40. 40.What is ∛216? =

Answer key

  1. 5
  2. 14
  3. 216
  4. 27
  5. 1331
  6. 216
  7. 3375
  8. 125
  9. 1331
  10. 6
  11. 8
  12. 21
  13. 18
  14. 27
  15. 343
  16. 9
  17. 3375
  18. 4
  19. 5832
  20. 125
  21. 8000
  22. 1000
  23. 2744
  24. 3
  25. 20
  26. 125
  27. 2197
  28. 9
  29. 25
  30. 13
  31. 8
  32. 64
  33. 4
  34. 4
  35. 13
  36. 125
  37. 1728
  38. 17
  39. 512
  40. 6

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