From d way my doctor taught me wen I was pregnant,u count from d day of ur last period.Den you calculate by adding d number of days we have in a month.for instance if ur last menstural flow was on 17 Nov den if u count from dat 17 dat ur period started to 30 Nov is 14 days+Dec 31 days+,January 31 days+Feb 28 days,+ March 31 days + april 30 + may 31.like today's date is 15th wen u get to May u write 15 instead of 31.After u add all up n divide by d number of d month we are in now in order to get