Incorrect Calculation of Payroll

Dear Experts,

I have a new employee whose joining date is 11 May 2015. His Basic Salary is 3000/- .

Now when I run his payroll (for the number of days he has worked in the month of May), the basic shud be 2160/- but the system is calculating the basic as 2077. which of course is incorrect.

Let me try and explain the number of working days:

Total days in the month of May: 31

Number of Sundays: 05

Number of Holidays: 01

Total Number of Working days: (31-5-1) = 25

Employees Joining Date: 11 May

Total number of days the employee has worked: 18

Actual Basic Salary: 3000/-

Basic tobe received: 2160/-

Current Basic receiving (Which is incorrect): 2077/-

Plz help me correcting this.

I run INDIA payroll

regards

Harriss