maxFractionDigits：小數第幾位
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
<input type="range" name="test" value='<fmt:formatNumber type="number" value="${test/ 10}" maxFractionDigits="1" var="num"/>'>參考資料：
https://docs.oracle.com/javaee/5/jstl/1.1/docs/tlddocs/fmt/tld-summary.html