Okay, here is a Chinese article with the title "When is ovulation on menstrual period number 4?":

For many women, determining when they are ovulating can be a confusing issue. Because most women's menstrual cycle is 28 days, and different people have different cycles and physical conditions. However, here are some ways to help women determine when they are ovulating:

First, calculate your menstrual cycle. Usually, a woman's menstrual cycle is measured in months, such as 28 days. Therefore, if the cycle is 28 days, the next menstrual period should be on October 4th. Then, subtract 14 days from October 4th, which is the woman's ovulation period.

Secondly, you can use body temperature measurement to determine your ovulation period. Women take their temperature every morning when they wake up and record changes in body temperature. Generally speaking, a woman's body temperature will rise during ovulation, and the body temperature on this day will usually reach 37 degrees.

Third, you can use a calendar to determine your ovulation period. Mark a woman's menstrual cycles on a calendar and record the day of each cycle. Then, in a woman's menstrual cycle, mark the day when her body temperature rises. This day is the woman's ovulation period.

The above methods are only a reference, and the actual situation may be different. Therefore, if a woman is unsure about her ovulation period, it is best to seek advice from her doctor or other professional.

To sum up, determining your ovulation period takes some time and patience, but by using these methods, women can better understand their health and fertility potential.