A cycle lasts 28 days so count 28 days from the first day of your last period
If you count the rocket propulsion developed by cephalopods, rockets have existed since the Silurian period.
I guess that could count as a period
No, because you did not have it. Therefore the period before that one was your last period.
Even though some women can ovulate slower or faster than others, the normal count between periods is to count 28 days from the day you BEGIN a period.
well, this is basically my schedule.homeroom ( doesn't count as a period)ScienceLanguage ArtsMathSocial studiesLunch ( doesn't count as a period)Choir ( my elective)P.E
most women have a 28 day cycle, you count from Day One when you start your period to get the date for your next period
Yes, you still count
Not unless you count pregnancy.
Just count the wavelengths distance.
Count 10 days after your period =D
That depends on whether you're using the "long count" or the "short count". In the short count, it would be 18. In the long count, it would be 24.