Distinct digits (0 to 9) and an asterisk (*) represent distinct letters.
The letters N
and R were Not Replaced and they appear in their correct locations in the text.
Choosing the last of these as being the most likely, the most likely filling in of the remainder would be:
I AM ILL AT THESE NUMBERS
A Google search brings up the play Hamlet. Reading the Project Gutenberg plain-text copy of this play shows Polonius reading this as part of a letter from Hamlet to Ophelia.
rest of the solution (spoiler)
