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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 87 · 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.What is 14³? =
  2. 2.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  3. 3.What is 12³? =
  4. 4.Which of these is a perfect cube? (a) 36 (b) 51 (c) 27
  5. 5.What is ∛12167? =
  6. 6.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  7. 7.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  8. 8.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  9. 9.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.What is ∛125? =
  11. 11.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  12. 12.What is ∛2744? =
  13. 13.Which of these is a perfect cube? (a) 343 (b) 462 (c) 406
  14. 14.Which of these is a perfect cube? (a) 3555 (b) 3375 (c) 3687
  15. 15.What is 11³? =
  16. 16.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  17. 17.What is ∛9261? =
  18. 18.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  19. 19.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  20. 20.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  21. 21.What is 13³? =
  22. 22.Which of these is a perfect cube? (a) 2744 (b) 2926 (c) 3258
  23. 23.What is 8³? =
  24. 24.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  25. 25.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  26. 26.What is 5³? =
  27. 27.Which of these is a perfect cube? (a) 729 (b) 774 (c) 913
  28. 28.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.Which of these is a perfect cube? (a) 1566 (b) 1331 (c) 1612
  30. 30.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  32. 32.What is 3³? =
  33. 33.What is ∛1000? =
  34. 34.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.What is ∛27? =
  37. 37.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  38. 38.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  39. 39.What is ∛3375? =
  40. 40.What is ∛5832? =

Answer key

  1. 2744
  2. 216
  3. 1728
  4. 27
  5. 23
  6. 2
  7. 27
  8. 3
  9. 64
  10. 5
  11. 4
  12. 14
  13. 343
  14. 3375
  15. 1331
  16. 2
  17. 21
  18. 5
  19. 8
  20. 12
  21. 2197
  22. 2744
  23. 512
  24. 9
  25. 19
  26. 125
  27. 729
  28. 27
  29. 1331
  30. 7
  31. 5
  32. 27
  33. 10
  34. 27
  35. 216
  36. 3
  37. 3
  38. 49
  39. 15
  40. 18

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