A month is any one of the twelve periods of time into which the year is divided. We all know well that a year normally comprises 365 days, but a leap year has 366 days. When we divide 365 or 366 by 12, we get fractional values only, i.e., 30.41 and 30.5 only. However, in the English Calendar, some months have 30 days, some have 31 days, and the month of February has 28 or 29 days. In the Tamil Calendar, some months even have 32 days. Therefore, the number of days a month comprises is a matter of approximation for calculation purposes.
Wages and Salary in Employment
In the field of employment, wages or salary is, in general, the compensation given to the person employed in consideration of the work done by him or her. It may be based on the quantity of work done, piece-rate, or time taken in terms of hours, days, weeks, months, or years, or a combination of quantity and time. It depends upon the nature of work or the nature of the employment relationship. When the employment relationship becomes continuous or permanent, a consistent level of efficiency is expected from the employee, and to maintain it, the wages paid by the employer have to include the day of rest. Therefore, for the sake of convenience of calculation, a month is assumed to have 30 days or 4 weeks (though a week actually has 7 days).
The Concept of Rest Days
Whether as a matter of religious impact or physical limitation, I don't know why the 7th day after continuous work for 6 days became a day of rest by convention and by law as well. By adding up the 26 days of actual work plus the 4 days of rest, a month is recognized to comprise 30 days as an economic reality for calculation purposes in the realm of employment. Regarding the justification given by Janardhan (with an element of well-founded doubt, of course), I would like to request him kindly to go through Rule 23 of the Minimum Wages (Central) Rules, 1950.
Regards