(i) 192
Resolving 192 into Prime factors as follows
Here, factor 3 is not in group of three.
∴ The smallest number by which 192 should be divided to make it perfect cube is 3.
(ii) 135
Resolving 135 into Prime factors as follows
Here, factor 5 is not in group of three
∴ The smallest number by which 135, should be divided to make it perfect cube is 5.