re = /^\s*\?\s*(.*?)\s+\d+(?:\.\d+)?[kM]?/m
str = ' ? 5girls 57k
? acoustic guitar 1.4k
? bass guitar 4.2k
? black choker 144k
? black dress 227k
? black footwear 275k
? black pants 133k
? black ribbon 128k
? black shirt 201k
? black shorts 117k
? blue eyes 1.7M '
subst = '$1,'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html