var imagenumber = 5 ;
var randomnumber = Math.random() ;
var rand1 = Math.round( (imagenumber-1) * randomnumber) + 1 ;
images = new Array
images[1] = "../image/photos/b1.jpg"
images[2] = "../image/photos/b2.jpg"
images[3] = "../image/photos/b3.jpg"
images[4] = 
"../image/photos/b4.jpg"
images[5] = 
"../image/photos/b5.jpg"
var image = images[rand1]
document.write('<IMG SRC="' + image + '">')