Accept an answer of around 90 or -90
# We do not want a vector
if ($submission=~/\,/) { return 'EXTRA_ANSWER'; }
# No units needed
if ($submission=~/^\d+\s+\w+$/) { return 'UNIT_NOTNEEDED'; }
# Need a numerical answer here
if ($submission!~/^[\d\.\-]+$/) { return 'WANTED_NUMERIC'; }
$difference=abs(90-abs($submission));
if ($difference==0) { return 'EXACT_ANS'; }
if ($difference < 0.001) { return 'APPROX_ANS'; }
return 'INCORRECT';