Pay sales tax with the Retail Sales Tax Return For Occasional Sales (DR 0100A) on the tangible personal property included in the purchase of the business by the 20th day of the month following the sale.
So, to avoid pregnancy she has to better avoid unprotected sexual intercourse in this period. The rest of the days i.e., starting from menstruation to the 10th day and again from 21st day up to menstruation are the safe days or the safe period to avoid pregnancy.
She can miss seven active pills without the risk of ovulation (which is what occurs in the pill free interval). Therefore, the least dangerous time for a woman to miss pills is in the middle of the packet and the most dangerous time is at the beginning or end of a packet. See the pill and 'periods' section.