Number of days in 6 months

[immihelp]

I would like to request you to kindly enlighten me by answering my question.

How many days are there in 6 months? Whether 6 months mean 180 days? I think it is not correct to say that 180 days make 6 months. It should be 182 days to make 6 months.
But how to support the argument that 182 days make 6 months.

[immihelp]

There may be 180, 181, 182, 183 or 184 days in 6 months, depending upon the start date and end date.