Put 2.{_{6}**(•)}, 2.{_{6}**(•)}3{_{1}**(•)}, 2.6{_{3}**( •)}{_{1}**(•)}, 2.{_{6}**(•)}{_{3}**(•)}, 2.636 These five numbers are in descending order Arranged in order, what is the number in the middle.
把2.{_{6}**(•)}、2.{_{6}**(•)}3{_{1}**(•)}、2.6{_{3}**(•)}{_{1}**(•)}、2.{_{6}**(•)}{_{3}**(•)}、2.636这五个数按从大到小的顺序排列，中间一个数是多少．
<result>2.636</result>