1. <!DOCTYPE html>
    2. <html lang="en">
    3. <head>
    4.     <meta charset="UTF-8">
    5.     <title>4-3Math-round练习</title>
    7.     <script type="text/javascript">
    9.         //四舍五入
    10.         alert("25.5：" +Math.round(25.5));
    11.         alert("25.4：" +Math.round(25.4));
    12.         alert("-25.5：" +Math.round(-25.5));
    13.         alert("-25.4：" +Math.round(-25.4));
    15.     </script>
    17. </head>
    18. <body>
    20. </body>
    21. </html>