var ran1 = Math.random(); // number 0 - < 1
var ran2 = 1000000 * ran1;
var adRandNum1 = Math.floor(ran2);

var ads = '<br /><a href="http://ad.doubleclick.net/jump/fim.cyd/other;pos=;tile=6;sz=120x60;ord=' + adRandNum1 +'?" target="_new"><img src="http://ad.doubleclick.net/ad/fim.cyd/other;pos=;tile=6;sz=120x60;ord=' + adRandNum1 +'?" border="0"/></a><br />';
document.write(ads);