document.write('<div align="center">');
var textnumber = 5;
var randomnumber = Math.random() ;
var rand1 = Math.round( (textnumber-1) * randomnumber) + 1 ;
text = new Array

text[1] = '<script language="javascript" src="http://www.anunciosyclasificados.info/script/botemania600.js"></script>'
text[2] = '<script language="javascript" src="http://www.anunciosyclasificados.info/script/alternativob600.js"></script>'
text[3] = '<script language="javascript" src="http://www.anunciosyclasificados.info/script/affutd600.js"></script>'
text[4] = '<script language="javascript" src="http://www.anunciosyclasificados.info/script/dating600.js"></script>'
text[5] = '<script language="javascript" src="http://www.anunciosyclasificados.info/script/eroadvertising600.js"></script>'

var mytext = text[rand1]
document.write(text[rand1]);

document.write('</div>');