// JavaScript Document

var a = Math.ceil(Math.random() * 10);
var b = Math.ceil(Math.random() * 10);       
var c = a + b

function drawCatpcha()
{
    document.write("Cuanto suman "+ a + " + " + b +"? ");
    document.write("<input id='captchaUser' name='captchaUser' type='text' maxlength='2' size='2'/>");
    document.write("<input id='captchaCPU' name='captchaCPU' type='hidden' value='"+c+"' />");	
}    

function checkCatpcha(){
   var d = document.getElementById('captchaUser').value;
   if (d == c) return true;        
   alert("La suma no es correcta.");
   return false;
}