That is 1 CE = 1 AD, and 2016 CE = 2016 AD. The word common simply means that it is based on the most frequently used calendar system: the Gregorian Calendar. Both measure the number of years before the approximate birthday of Yeshua/Jesus. Designation of a particular year in BC and BCE also have identical values.
Francium is a chemical element with symbol Fr and atomic number 87. It was formerly known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon. As an alkali metal, it has one valence electron. Bulk francium has never been viewed.
This is called the half-life of the radioactive isotope. There are two definitions of half-life, but they mean essentially the same thing. Different radioactive isotopes have different half-lives. For example, the half-life of carbon-14 is 5,715 years, but the half-life of francium-223 is just 20 minutes.