Pension — pension calculation system

Address:

New Delhi, Delhi

Ppo no. Ds/shd/00006104
Sir,
I am greeting my pension regular.
Some how i came to know that my pension is less (Only 6/- rs)
Some good person told me that there is calculation mistake.
While counting actual service proper year is wrong
Ie 15 year 11 months 12 days = 15 or 16 years??
If calculation is by 16 years then it is 6 rs more
And if we take as at is then it is 6 rs less.
I want to know the correct method.
If service is less then 6 months (To ignor)
If service is more then 6 month (Count as 1)
Which is correct?? Method.