Index: captcha.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/captcha/captcha.module,v
retrieving revision 1.90
diff -u -r1.90 captcha.module
--- captcha.module	21 May 2009 11:46:34 -0000	1.90
+++ captcha.module	21 May 2009 12:21:01 -0000
@@ -499,6 +499,7 @@
           '#size' => 4,
           '#maxlength' => 2,
           '#required' => TRUE,
+          '#process' => array('captcha_math_process'),
         );
         return $result;
       }
@@ -522,3 +523,8 @@
       break;
   }
 }
+
+function captcha_math_process($element, $edit, &$form_state, $complete_form) {
+  $element['#value'] += 1;
+  return $element;
+}