I have encountered one such problem in this link
https://gateoverflow.in/1219/gate2007-21
There is a video attached in the comments about the isomorphism part but I am unable to understand it clearly
The number of Abelian groups of order P^k (P is prime) is the number of partitions of k.
Prime factorization of 16 = 2^4
The partitions of power i.e.., 4 = {1+1+1+1},{2+1+1},{2+2},{3+1},{4}
So total partitions =5
Answer =5
The tests are there but it ain't free. Cost is...