DB<94> $_ =" some text No. 345 other text No. 123 end text"

  DB<95> p
 some text No. 345 other text No. 123 end text
  DB<96> s/(No.) (\d)(\d)(\d)/$1 \\$nums[$2]-$nums[$3]-$nums[$4]/g

  DB<97> p
 some text No. \three-four-five other text No. \one-two-three end text