Hello, this is a Uranium 235 decay test, some interesting things about this deck: The probability that actinium 227 becomes francium 223 is 2% And for Francium to become Astatine it is 0.02% The least likely decay chain is: U235-Th231-Pa231-Ac227-Fr223-At219-Bi215-Po215-At215-Bi211-Po211-Pb207 Note: The less improbable decay chains are probably poorly programmed due to low probability. If you want to access the deck information, some variables or names may be difficult to understand (end of comment).