Getting last cell value in column

Try this.....
In A55

=INDEX($A$3:$A$54,MATCH(1E+307,$A$3:$A$54))

Is this what you are trying to achieve?

You could also use LOOKUP like this:

=LOOKUP(1E+307,A3:A54)

You're welcome.
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@galeocerdo
Probably you didn't read OP's first post. He wants formula in A55 and wants to get last value entered in the range A3:A54.

Your formula has two limitations.....
1) It cannot be placed in A55, as it will cause circular reference.
2) It will return wrong result if some of the cells are blank in col. A.

Hope this helps.