sub m1{1+4*y/VLD//.E.ord()x3%75%50%4}

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can be improved to 
sub m3{5**y/VLD//.E.ord()x3%75%50%4}

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This is much longer than yours, but I thought I'd still mention it: 

sub b0{(1e3,10,5,1,100,500,50)[ord()%87%7]}

[download]

Update: a new one that's only one character too long 

sub b1{M1E3D500C100L50X10V5I1=~$_;$'}

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In reply to Re: Golf: Magic Formula for Roman Numerals by ambrus
in thread Golf: Magic Formula for Roman Numerals by eyepopslikeamosquito

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