Why is this not 0 on 50g or Prime?

[BartDB]

try the following:

\[\frac { 1 }{ \infty +\left | \cfrac { 1 }{ 0 } \right | } \]

Also in WA:
http://www.wolframalpha.com/input/?i=1%2...bs(1%2F0))


EDIT:
The reason for the WA answer is that 1/0 gives "complex infinity" which cannot be added to real infinity (definition of Complex Infinity: a complex quantity with infinite magnitude but indeterminate phase) .

The 50G also recognises 2 infinities: see AUR p3-289
"The calculator recognizes two kinds of infinity: signed and unsigned. Evaluating '1/0' gives an unsigned infinity. Selecting infinity from the keyboard ... returns '+inf' and the sign can be changed. Calculations with the unsigned infinity return unsigned infinity or ? as their result. Calculations with the signed infinity can return ordinary numeric results, as in the example. Positive infinity and unsigned infinity are equal if tested with ==, but are not identical if tested with SAME."