Learning Path Question...

I was presented with the following learning path question. I initially selected the 3rd option but it was marked wrong. Why? Surely, options 3 and 4 are logically equivalent? Am I missing something here?
1 answers

The only reason I can think of that would make answers 3 and 4 different is that a type conversion takes place by performing the calculation. If the period token is a string and by the mutliplying by 1 a type conversion to integer takes place then only 4 would work as substracting a string would lead to an error.