Adding Strings and Numbers in JavaScript | 10

I was reading the re-introduction to JavaScript on MDN and in the section Numbers it said that you can convert a string to a number simply by adding a plus operator in front of it.

For example:

+"42" which would yield the number output of 42.

But further along in the section about Operators it says that by adding a string "something" to any number you can convert that number to a string. They also provide the following example which confused me:

"3" + 4 + 5 would presumably yield a string of 345 in the output, because numbers 4 and 5 would also be converted to strings.

However, wouldn't 3 + 4 + "5" yield a number of 12 instead of a string 75 as was stated in their example?

In this second example in the section about operators wouldn't the + operator which is standing in front of a string "5" convert that string into number 5 and then add everything up to equal 12?