In 2017 we just do: $ perl6 -e 'say Ⅻ / Ⅲ' 4
care to explain why this works?
That Perl allows them in integer literals is strange, but also logical in a weird way. (Now I wonder what other number systems it supports.)
EDIT: Ok, so I installed perl6 (rakudo) just to test this out, and it apparently doesn't work out of the box. Pity.