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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 202 · 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) 31 (b) 27 (c) 41
  2. 2.What is 6³? =
  3. 3.What is ∛15625? =
  4. 4.Which of these is a perfect cube? (a) 1520 (b) 1331 (c) 1616
  5. 5.Which of these is a perfect cube? (a) 3581 (b) 3783 (c) 3375
  6. 6.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  7. 7.What is ∛512? =
  8. 8.What is ∛8? =
  9. 9.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  10. 10.What is 19³? =
  11. 11.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  12. 12.What is 9³? =
  13. 13.Which of these is a perfect cube? (a) 1855 (b) 1785 (c) 1728
  14. 14.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  15. 15.What is 3³? =
  16. 16.What is ∛729? =
  17. 17.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  18. 18.What is ∛4913? =
  19. 19.What is 11³? =
  20. 20.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  21. 21.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  22. 22.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  23. 23.What is 7³? =
  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 the smallest whole number by which 448 must be divided to get a perfect cube?
  26. 26.What is 17³? =
  27. 27.What is 14³? =
  28. 28.Which of these is a perfect cube? (a) 426 (b) 343 (c) 380
  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 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  32. 32.Which of these is a perfect cube? (a) 2744 (b) 3121 (c) 3228
  33. 33.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  34. 34.What is ∛27? =
  35. 35.What is ∛343? =
  36. 36.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  37. 37.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  38. 38.Which of these is a perfect cube? (a) 216 (b) 258 (c) 285
  39. 39.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 16 must be divided to get a perfect cube?

Answer key

  1. 27
  2. 216
  3. 25
  4. 1331
  5. 3375
  6. 2
  7. 8
  8. 2
  9. 12
  10. 6859
  11. 49
  12. 729
  13. 1728
  14. 13
  15. 27
  16. 9
  17. 17
  18. 17
  19. 1331
  20. 2
  21. 7
  22. 49
  23. 343
  24. 27
  25. 7
  26. 4913
  27. 2744
  28. 343
  29. 27
  30. 8
  31. 2
  32. 2744
  33. 9
  34. 3
  35. 7
  36. 7
  37. 125
  38. 216
  39. 15
  40. 2

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