I didn't use to have this problem but it seems like | started appearing after math stuff. (I use PGML if that matters.)
I've attached a screenshot of the problem. Here's the
source for the problem....
DOCUMENT();
loadMacros(
"MathObjects.pl",
"PGstandard.pl",
"PGML.pl",
"PGcourse.pl",
"parserNumberWithUnits.pl",
"contextArbitraryString.pl",
"parserMultiAnswer.pl",
"parserPopUp.pl",
"contextInequalities.pl",
"PGgraphmacros.pl",
);
TEXT(beginproblem());
$showPartialCorrectAnswers = 1;
######################################################################
Context("Numeric") ; Context()->flags->set(tolerance => 0.01);
BEGIN_PGML
Calculate [`\int_{-3}^{3} \sqrt{9 - x^2} dx`].
Hint: What is the shape of the corresponding area?
[________________________]{Compute("9*pi/2")}
END_PGML
######################################################################
ENDDOCUMENT();
