divs = ['rotate1','rotate2','rotate3', 'rotate4', 'rotate5'];

function hideDivs() {
for (var i=0; i<divs.length; i++)
document.getElementById(divs[i]).style.display = 'none';
}

function showDiv() {
hideDivs(); //hide them all before we show the next one.
var randomDiv = divs[Math.floor(Math.random()*divs.length)];
var div = document.getElementById(randomDiv).style.display =
'block';

//setTimeout(showDiv,8000); //set a delay before showing the next div
}