<html>
<head>
<style type="text/css">
div {
width:200px;
background: red;
line-height: 30px;
height:30px;
text-align:justify;
}
div:after {
display:inline-block;
content:'';
padding-left:100%;
}
</style>
</head>
<body>
<div>数量</div>
</body>
</html>