You haven't reached the computer yet.
The numbers GSpotFrenzy listed, and the parentheses, are given to you. You just have to plug in +, -, * or /.
So, the question at hand is replace the '_' below with an operator to make the statement true.
(6 _ 2) _ 8 _ 9 _ 1 = 13
<{POST_SNAPBACK}>
Ah. Then give (6/2)*8-9*1 (and /1) a try. Silly developers must just be doing string matching rather than actually calculating the result.
I'm glad I read this spoiler... I would have really have been pulling my hair out if I tried a valid answer while playing the game and it failed.