var howMany = 7
var win = new Array(howMany) 

win [0] = "images/tips.jpg"; 
win [1] = "images/tips2.jpg "; 
win [2] = "images/tips3.jpg "; 
win [3] = "images/tips4.jpg";
win [4] = "images/tips5.jpg";
win [5] = "images/tips6.jpg";
win [6] = "images/tips7.jpg";

function rndnumber(){ 
var randscript = -1 
while (randscript < 0 || randscript > howMany || isNaN(randscript)){ 
randscript = parseInt(Math.random()*(howMany)) 
} 
return randscript 
} 

quo = rndnumber() 
quox = win[quo] 

document.write("<img src="+quox + ">"); //