For this type of sentence, the verb behind is omitted. It's like
"how many dollars do you have?" "I have ten (dollars)". The dollars
is omitted, because it's assumed that the listener knows what you
are talking about; similarly for this case.
eg. The girl goes to the same school as ____ (do).
In this case, you should put "I" instead of "me", because the
sentence will read "The girl goes to the same school as me do"
which is wrong.
In this case it's a case of too infrequent usage. People use
"me" too much, so much so that they take the "me" as correct and
say that "I" is wrong.
I'm no language guru, so I stand corrected. But I'm very sure
about this.
