function MathRandom ()
{
    var p_random = new Array();
    p_random[0] = "r-1";
    p_random[1] = "r-2";
    p_random[2] = "r-3";
    //p_random[2] = "r-3";
    var Content = Math.floor(Math.random() * p_random.length);
    document.getElementById(p_random [Content]).style.display = 'block'; 
}