<div class="foo">
<div>lorem ipsum</div>
<div>lorem ipsum</div>
<div>lorem ipsum</div>
<div>lorem ipsum</div>
<div>lorem ipsum</div>
<div>lorem ipsum</div>
</div>
body{counter-reset:bar;}

.foo div:before{
counter-increment:bar;
content:"第" counters(bar,"")"番目";
margin-right:20px;
}

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