/// or // should be more like s/// or m//

but what is $foo // or $brr /// (nothing if i remember correctly)

 $foo // expr has nothing to do with regex

oh "divide" by a regex, mmmkay, maybe something like

$_ = "2k4";
print ( 49 / /\d/); #?
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(i can't see how what you're suggesting can occur, or i'm misunderstanding)