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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 836 · 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 the smallest whole number by which 128 must be multiplied to get a perfect cube?
  2. 2.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.Which of these is a perfect cube? (a) 47 (b) 48 (c) 27
  4. 4.Which of these is a perfect cube? (a) 216 (b) 232 (c) 306
  5. 5.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  6. 6.What is ∛12167? =
  7. 7.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  8. 8.Which of these is a perfect cube? (a) 1515 (b) 1331 (c) 1390
  9. 9.Which of these is a perfect cube? (a) 3375 (b) 3660 (c) 3908
  10. 10.What is ∛2744? =
  11. 11.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.Which of these is a perfect cube? (a) 530 (b) 576 (c) 512
  13. 13.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  14. 14.What is 6³? =
  15. 15.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  16. 16.What is 8³? =
  17. 17.What is 18³? =
  18. 18.What is 17³? =
  19. 19.What is 10³? =
  20. 20.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  21. 21.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  22. 22.What is ∛2197? =
  23. 23.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  24. 24.What is ∛512? =
  25. 25.What is ∛729? =
  26. 26.Which of these is a perfect cube? (a) 1992 (b) 1892 (c) 1728
  27. 27.What is ∛8000? =
  28. 28.What is 13³? =
  29. 29.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.What is ∛9261? =
  31. 31.What is ∛10648? =
  32. 32.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  33. 33.What is ∛27? =
  34. 34.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  35. 35.Which of these is a perfect cube? (a) 1109 (b) 1231 (c) 1000
  36. 36.Which of these is a perfect cube? (a) 131 (b) 138 (c) 125
  37. 37.What is 7³? =
  38. 38.Which of these is a perfect cube? (a) 824 (b) 729 (c) 918
  39. 39.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  40. 40.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?

Answer key

  1. 4
  2. 27
  3. 27
  4. 216
  5. 4
  6. 23
  7. 11
  8. 1331
  9. 3375
  10. 14
  11. 8
  12. 512
  13. 4
  14. 216
  15. 49
  16. 512
  17. 5832
  18. 4913
  19. 1000
  20. 49
  21. 25
  22. 13
  23. 10
  24. 8
  25. 9
  26. 1728
  27. 20
  28. 2197
  29. 8
  30. 21
  31. 22
  32. 18
  33. 3
  34. 12
  35. 1000
  36. 125
  37. 343
  38. 729
  39. 3
  40. 7

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