--- loncom/homework/default_homework.lcpm	2011/10/06 17:15:40	1.161
+++ loncom/homework/default_homework.lcpm	2013/01/21 06:16:50	1.163
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA 
 # used by lonxml::xmlparse() as input variable $safeinit to Apache::run::run()
 #
-# $Id: default_homework.lcpm,v 1.161 2011/10/06 17:15:40 raeburn Exp $
+# $Id: default_homework.lcpm,v 1.163 2013/01/21 06:16:50 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -816,6 +816,7 @@ sub cos { CORE::cos(shift) }
 sub exp { CORE::exp(shift) }
 sub int { CORE::int(shift) }
 sub log { CORE::log(shift) }
+sub ln { CORE::log(shift) }
 sub atan2 { CORE::atan2($_[0],$_[1]) }
 sub sqrt { CORE::sqrt(shift) }
 
@@ -1032,6 +1033,17 @@ sub format_significant_figures {
     $number = abs($number);
     # needed to correct for a number greater than 1 (or
     my $power = ($number < 1) ? 0 : 1;
+    if ($power && $number =~ /^\d+$/) {
+        my $nonzeros = $number;
+        $nonzeros =~ s/0+$//;
+        if (length($number) - length($nonzeros) > 1) {
+            # convert to exponential form
+            my $n = $sig-1;
+            my $numSig = sprintf('%.' . $n . 'E', $number);
+            # return number with sign
+            return $sign.$numSig;
+        }
+    }
     # could round up. Take the integer part of log10.
     my $x10 = int(log($number)/log(10));
     # find number with values left of decimal pt = # of sign figs.