The fragment that I posted Louis De Alcasar is said to have used a similar type text(renders the mark 616 instead of 666) in his work. Now Irenaeus spoke much about this in A.H.,he said that it was an error on the part of the translator.
He in the preface to A.H., book 1,chapter 2 begins to Identify the origins of these type writings as,,, "the commentaries,as they call them,of the disciples of Valentinus",,and explains that the heresy was promulgated by Ptolemaeus and his disciples a school that budded off from Valentinus.
In A.H. book 1 chapter 3.2 Irenaeus points out their teachings of the "Iota and Etta"(in the Gnostic belief). In A.H. book 5 chapter 30.1 Irenaeus explains this number 616 and that it reduces the number by 50 to 616 because they(Valentinus/Ptplemaeus) had altered the number.
Also in A.H. book 5 chapter 30.1 Irenaeus refers to "most approved and ancient copies" so there are both copies he saw of Revelation and commentaries that contained the errors/change containing both the letters "Iota and Etta".
In the fragment in the third line from the top there is found "Etta",looks like the upper case letter "H" in English. Then Chi,Iota,Sigma(616) instead of Chi,Xi,Sigma(666) which should suffice to establish that the fragment is most probably an commentary instead of a copy of the Revelation because of the "Etta" preceding the number instead of arithmos
http://biblehub.com/greek/706.htm ,,,so "H",Etta not being the last letter of the word number strongly indicates that this does not follow the wording in the text of Revelation 13:18 KJV .
but then if someone could not interpret this for their own-selves well then they have no choice but to hope that there is an interpreter to do so. I mean no offense but I am not Catholic nor preterit,,then again I can read the text.
p.s. I'll include A.H.
http://www.newadvent.org/fathers/0103.htm from a source you feel comfortable with so you can check my quotes,,,,