$ perl -E 'say sprintf q{%.uC}, ( 75 - 32 ) / 1.8;'
23C
$ perl -E 'say sprintf q{%fC}, ( 75 - 32 ) / 1.8;'
23.888889C
$ perl -E 'say sprintf q{%.1fC}, ( 75 - 32 ) / 1.8;'
23.9C
$