<body>
<div class="photo_numb"></div>
<div class="photo_numb"></div>
<div class="photo_numb"></div>
<div class="photo_numb"></div>
<div class="photo_numb"></div>
<script>
var
a = document.querySelectorAll('.photo_numb'),
i = 0,
j = 0;
while (i < a.length) {
j+=1;
a[i].innerText = j;
i++;
}
</script>
</body>