Find the smallest number by which 192 must be divided to obtain a perfect cube.

$192=\underline{2\times 2\times 2}\times \underline{2\times 2\times 2}\times 3$

Here, 3 is left after grouping in triplets. So, 192 is not a perfect cube. 

In the factorisation 3 appears only one time. If we divide the number by 3, then it will become a perfect cube.

So, $192÷3=\underline{2\times 2\times 2}\times \underline{2\times 2\times 2}=64$ is a perfect cube.
Hence, the smallest natural number by which 192 should be divided to make it a perfect cube is 3.