If it is for the jan - dec calendar year then you can do as follows :
6/12* (no of months remaining and in your case it will 10 months)
Secondly if your company falls under S&E act then, as per new Maharashtra S&E act you need to give 8 days as casual leave instead of 8.
4th May 2018
As Manoj mentioned in his post, it is .5*balance months.
It is impacted by state policy and company policy.
State defines the minimum number of days to be granted against sick and casual leaves.
Internal leave policy decides on when to grant leaves like, annually or half yearly or quarterly or monthly.
6th May 2018 From India, Chennai