[SteveDallas]

Originally Posted by Ibram

Bullshit. Any cites of these calculators and textbooks? I've never heard this.

The root of all this is ambiguous use of the "/" in a single-line context, where properly-typeset multi-line usage would result in either

  2  
----
 5x

or

 2
--- x
 5

Any sensible reinterpretation of one of these into a single line would include appropriate parentheses or other clarification to make it clear how the calculation is carried out. As noted earlier, the entire point of the 48-whatever example is to start an argument.

In fact, I dare say that incorrect interpretation of the fraction bar by bogus separation of terms in numerators and denominators, for example

 x + 5     x     
------- = ---  +  5
   2       2

is a very common student error, and contributes to the misinterpretation of typographical disasters such as we're discussing.