Hi Ritu,
A salary hike can be made on different bases, for example, based on past performance or annual salary increments as per the company's policy. However, irrespective of that, the hike is generally done for future salaries. So, if a person receives a 16% increment and assuming their salary is INR 1,00,000 per annum, the revised salary will be INR 1,16,000 per annum, and monthly it will be INR 1,16,000/12.
I don't think the number of months a person has been working is important for calculating the revised salary unless otherwise specified.
Regards,
Sanjay