I had this thought before :)

now perl gives warning

Argument "0x41" isn't numeric in printf
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Very clean, things we know are numbers and can unambiguously identify as numbers, we treat as numbers, all other stuff we warn about

But if definition of numeric was expanded to include more ambiguous num formats, then perl would need a new warning

treating "0x41" as numeric , might be wrong thing to do, silence with 
+"no warnings q/extranumeric/;"
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I'm confused why perl-diddler hasn't posted use extranumeric; yet :D