User blog comment:Planterobloon/Noob question about the FGH/@comment-28606698-20171214171932

If you are analysing some new notation, then you should move step by step from to estimate the correspondence between elements of the notation   and ordinals of the fast-growing hierarchy beginning from the least ordinals. If a number is written in some well-known notation, then all is much simplier - this correspondence already known.