His solutions works while your does not. I ran them both in irb. This is because...

jeltz on Nov 15, 2012 | parent | context | favorite | on: FizzBuzz Still Works

His solutions works while your does not. I ran them both in irb. This is because "string << integer" does not do what you think it does. It treats the integer as character code.

  "" << 0x41 # => "A"