Write a method separate_comma which takes an integer as its input and returns a comma-separated integer as a string.

commas1.rb

def separate_comma(number)
  number.to_s.reverse.gsub(/(\d{3})(?=\d)/, '\\1,').reverse
end

commas2.rb

def separate_comma(number)

  array = number.to_s.reverse.split(//)
  len = array.length

  if len<=6
    n = 0
  elsif len%2 == 0
    n = 1
  else 
    n = 2
  end



  if len < 4
    return array.join.reverse.to_s  
  else
    i  = 3
    while i < len+n do
      array.insert(i, ',')
      i += 4
    end
  end

  return  array.join.reverse.to_s

end