--- loncom/homework/math_parser/ENode.pm	2017/01/19 19:24:57	1.4
+++ loncom/homework/math_parser/ENode.pm	2017/01/27 20:24:26	1.5
@@ -746,7 +746,12 @@ sub toTeX {
                     }
                 }
                 when ("!") {
-                    return($c0->toTeX()." !");
+                    my $s = $c0->toTeX();
+                    if ($c0->type == OPERATOR) {
+                        $s = "(".$s.")";
+                    }
+                    $s .= " !";
+                    return $s;
                 }
                 when ("%") {
                     return($c0->toTeX()." \\% ".$c1->toTeX());
@@ -805,6 +810,14 @@ sub toTeX {
                 when ("sqrt") {   return "\\sqrt{".$c1->toTeX()."}"; }
                 when ("abs") {    return "|".$c1->toTeX()."|"; }
                 when ("exp") {    return "\\mathrm{e}^{".$c1->toTeX()."}"; }
+                when ("factorial") {
+                    my $s = $c1->toTeX();
+                    if ($c1->type == OPERATOR) {
+                        $s = "(".$s.")";
+                    }
+                    $s .= " !";
+                    return $s;
+                }
                 when ("diff") {
                     if (scalar(@children) == 3) {
                         return "\\frac{d}{d".$c2->toTeX()."} ".$c1->toTeX();