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.
For americium-241, it is known that half of the atoms decay in 458 years. Therefore, 458 years is the half-life of americium-241. Every radioactive element has a different half-life, ranging from fractions of a second to millions of years, depending on the specific isotope.