Oddly enough, using regular expression:

[Nn][Oo]\.

works.  It requires that the N O be followed by the period, and in any instance where it is you get Number.   There is an issue, though, if no is at the very end of a sentence.  I can't seem to find a way to effectively say, "but not at the end of a sentence," at least not yet.

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Brian - Windows 10 Pro, 64-Bit, Version 1903, Build 18362  

The color of truth is grey.

           ~ André Gide