Hi Shahul ,
Your requirement is such that there are two variables :
1. The sheets which need to be considered for the sum
2. The cells which need to be summed up
In a formula , both can be specified ; in a function , at least one can be specified.
If you want a subroutine , then both of the above will have to be hard-coded within the subroutine , and each time you add a month or you add a new sheet , you will have to make the changes within the code. Is this acceptable ?
Narayan