To find out the result, we have to divide 365 days by 28 days:
365 / 28 = 13,03571428571429
So we can see it's 13 lunar months with something extra. To find that something extra we can multiply 28 by 13 and then substract the result from 365:
365 - (13 * 28) =
= 365 - 364 =
= 1
So there are 13 lunar months and one day.
