--- loncom/homework/caparesponse/caparesponse.pm	2018/09/14 02:51:39	1.260
+++ loncom/homework/caparesponse/caparesponse.pm	2020/12/05 05:01:18	1.262
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # caparesponse definition
 #
-# $Id: caparesponse.pm,v 1.260 2018/09/14 02:51:39 raeburn Exp $
+# $Id: caparesponse.pm,v 1.262 2020/12/05 05:01:18 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -1065,7 +1065,23 @@ sub make_numerical_bubbles {
                      &Math::Random::random_uniform_integer(1,1,10);
     }
     for ($ind=0;$ind<$number_of_bubbles;$ind++) {
-	$bubble_values[$ind] = $answerfactor*($factor**($power-$powers[$#powers-$ind]));
+	my $exponent = $power-$powers[$#powers-$ind];
+	$bubble_values[$ind] = $answerfactor*($factor**$exponent);
+
+	# If bubble is for correct answer (i.e., exponent = 0), and value
+	# of $answerfactor * factor**$exponent is an integer with more than
+	# 15 digits, assign $answerfactor itself as bubble value.
+	# This prevents a "use fewer digits" issue on 64bit servers
+	# when correct answer is >= 1e+16, and when correct bubble is A.
+
+	if ($exponent == 0) {
+	    if ($bubble_values[$ind] =~ /^-?(\d+)$/) {
+		if (length($1) > 15) {
+		    $bubble_values[$ind] = $answerfactor;
+		}
+	    }
+	}
+
 	$bubble_display[$ind] = &format_number($bubble_values[$ind],
 					       $format,$target,$safeeval);
     }