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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 645 · 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.Which of these is a perfect cube? (a) 1907 (b) 1870 (c) 1728
  2. 2.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  3. 3.What is 13³? =
  4. 4.What is ∛2744? =
  5. 5.Which of these is a perfect cube? (a) 186 (b) 125 (c) 183
  6. 6.What is ∛343? =
  7. 7.What is 20³? =
  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) 2815 (b) 2870 (c) 2744
  10. 10.Which of these is a perfect cube? (a) 729 (b) 961 (c) 751
  11. 11.What is ∛125? =
  12. 12.What is ∛4913? =
  13. 13.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  14. 14.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  15. 15.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  16. 16.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  17. 17.What is ∛8000? =
  18. 18.Which of these is a perfect cube? (a) 387 (b) 343 (c) 450
  19. 19.What is 7³? =
  20. 20.What is ∛8? =
  21. 21.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  22. 22.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  23. 23.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  24. 24.What is ∛729? =
  25. 25.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 216 (b) 259 (c) 291
  27. 27.Which of these is a perfect cube? (a) 1632 (b) 1331 (c) 1660
  28. 28.What is ∛216? =
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is 5³? =
  34. 34.What is ∛15625? =
  35. 35.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  36. 36.Which of these is a perfect cube? (a) 27 (b) 28 (c) 33
  37. 37.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  38. 38.Which of these is a perfect cube? (a) 1284 (b) 1000 (c) 1266
  39. 39.Which of these is a perfect cube? (a) 683 (b) 662 (c) 512
  40. 40.What is the smallest whole number by which 4 must be divided to get a perfect cube?

Answer key

  1. 1728
  2. 2
  3. 2197
  4. 14
  5. 125
  6. 7
  7. 8000
  8. 125
  9. 2744
  10. 729
  11. 5
  12. 17
  13. 20
  14. 25
  15. 3
  16. 6
  17. 20
  18. 343
  19. 343
  20. 2
  21. 49
  22. 8
  23. 5
  24. 9
  25. 7
  26. 216
  27. 1331
  28. 6
  29. 27
  30. 125
  31. 9
  32. 8
  33. 125
  34. 25
  35. 7
  36. 27
  37. 11
  38. 1000
  39. 512
  40. 4

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