Very simple ...
Multiply 0.115×5=0.575 customs
0.115×49=5.6 omg
0.115×40=4.6 IRS
Continue in the same manner and then round off the numbers you get in the end.
Yaar, it ll get very clumsy to explain ... as I am doing from mobile.
IA. You ll see either we would have 6 omg seats, 0 pcs or 5 omg seats, 1 pcs.

Its my assessment, also as I am not a big fan of pcs so let me clear whether we have customs seat or not, atleast it doesn't affect me.
But it's a wonderful occupational group.