I had to reread it a few times to parse it. Its result of "adding" the uppercase of 1 that should be 11, not the uppercase itself. In other words, the result

I had to reread it a few times to parse it. Its result of "adding" the uppercase of 1 that should be 11, not the uppercase itself. In other words, the result of "makeUppercase" should be a string, not a number.